Glow plug ohms- mystery plugs

[peteinjp]

At 5 seconds the difference was the greatest. First pic is the ND plug and second is the VSP. The first figures at 5 seconds:

Nippon denso plug 24v @ 8.6a = 2.8ohms
VSP plug 24v @ 5.25a = 4.6ohms

So I can see how this relates to the cold resistance check that I did at first where the VSP was 2x the resistance of the ND. Remember also that with 4 plugs these figures will be multiplied by 4- albeit at a slightly lower voltage. So with about 3 amps difference between the plugs X 4 we're looking at a total of 12a difference in initial draw- quite a lot! ND plugs would be drawing about 34a where as the VSP would be at 21a. The voltage would be lower however I think we would still see a similar ratio of about 3/2 in terms of draw. And of course this will have a great affect on the controller in terms of glowing or not.

 

[peteinjp]

As time goes on the amperage decreases and the resistance increases. I could not get the exact same timing but I did the math based on the curve produced by the numbers I got and came up with this:

Seconds= 5.2 9.6 13.9 18.3
ND amps 8.6 7.2 6.63 6.24
Vsp amps 5.3 5.2 5.1 5.06

I kept the test to under 20 seconds as that fit the period of time relative to the voltage when using the controller. I did not want to melt these things!

So we can see that the VSP stays relatively consistent in terms of its draw throughout the duration of the test. In the end if we multiply this by 4 plugs we have a difference of 4.2 amps which means the Vsp plugs are drawing about 4/5ths the amperage of the ND's after almost 20 seconds.

As Tom and others have stated indeed the relation between resistance when cold and hot is not linearly related. My own thoughts are that the resistance measurements should be consistent between plugs.

I did make one mistake in an earlier statement. I retested the voltage at the buss bar with both sets of plugs and while indeed the ND plugs had lower voltage (due to their greater draw across the contoller) the numbers were not as I had posted before. Somewhere between the shop and the computer room I got mixed up.

In fact in situ on the engine the ND's ran at 19.5v after about 10 seconds pulling 22.3 amps. The Vsp units ran at 22V at 15.7a at 10 seconds. The Vsp's running at about 3/4 the draw of the ND's (first and second pic respectively.) This Lines up perfectly with the bench test which also showed the Vsp's draw to be 3/4's of the ND's at 9.6 seconds.

If anyone else out there has VSP's on a 2b Lets hear how they work for you. I'd also be interested in hearing from someone with a 12v manual glow system on any type of engine. I kinda wonder if this is not a case of parts number cross reference where one a number gets crossed over without regard to the actual specs. After all these might work fine in a more modern system that does not use a resistor to control voltage and simply goes with a timer. I dunno....

Well on a side note- having dealt with the glow plug issue and replaced the diaphragm in the pump as well as the pre pump- I feel I can say that I'm not totally a diesel newbie anymore.



Best!

Pete

 

[lostmarbles]

Well Pete...You clearly have skills/expertise, good tools/test-equipment, and "attention to detail". So you've now convinced me that your new plugs are indeed your problem. (Sorry it took so long ... but scepticism is inevitable when two people don't know each other.)

And now that you've exposed this problem (of correct-spec plugs drawing insufficient current for a glow controller to glow properly) .. I suspect the problem is unlikely to be restricted to just the VSP brand.

This morning (after reading your posts above) I was about to transfer my VSP PT104 plugs from my spare engine to my BJ40 for testing (to see if I can support your findings) .... but in the end I couldn't make myself do it. The reasons being:

• I've got too many other things I should be doing right now, and
• I don't like tampering with things that are working fine because each time you remove/refit something on a 30-year-old vehicle you risk damaging/deteriorating it (or something related to it).
• My plugs are of a different specification to yours anyway (and obviously of a different batch too because you couldn't have different specifications within the same batch).

BTW ... I think you may have stumbled on a problem affecting other MUD members.

For instance I know Joe Egolf's controller has never glowed despite apparently being able to start his BJ42 OK in cold weather and despite apparently having the correct-spec plugs fitted. (In fact I'll bring this thread to Joe's attention now in a PM.)

Great diagnosis work Pete



PS. We have to remember that while some people may say they are running new VSP plugs without problems ... they may not necessarily have a glow controller in their circuitry. AFAIK "glow controllers" were only used in L/C diesels up to 1982. And because the controllers are difficult/expensive to replace when they fail .. many of even these few older diesels have had "Wilson Switches" fitted and now run without glow-controllers.

 

[Joe Egolf]

Thanks Tom.I will go check things tomorrow on my cruiser.It started well this am -temp in the 20's with two 12 sec glows and manual[choke cable] Over inject and vroom ,fired right up. I'll do a little rersearch in the am as to old and new Glow Plug Brand etc.

 

[fatdiesel]

I must have gotten a hold of the same batch of VSP brand plugs as well, and purchased from the same member. 20.5 volts. installed last weekend and no glow. at first i thought my problems were with the slight use of anti sieze i put on the threads, but now im thinking otherwise.

 

[peteinjp]

Well Tom I figured as much as well. I want to keep the truck as original as possible so if I can find a set of plugs that work well with the controller then clearly I'd prefer to go with those. I have a feeling that this is something that you and many others can relate to. If in the end there is not a plug that I can find that works right then so be it. In that case knowing myself I'll probably want to tear into the controller and shorten the coil a bit. (ni-chrome wire can be bent and reshaped if you heat it to red. If not it will just break due to having gone thru so many heat cycles.) But just as you- there are many other things to do in terms of maintenance..... As for this part of the world it will soon be covered in snow so its a very busy season.

Joe and Fatdiesel let us know if what you find out! Are you guys both running 20.5V plugs on a 2b?



The seller is indeed in the process of searching for another brand or 20.v plugs and hopefully we'll be able to see some quantifiable results in the near future.


And with that I'd better get back to welding up some patch panels...... Gotta get this thing out and wheel it on Sunday!

Pete

 

[DieselLover]

Have been in close contact with Pete and been following this thread with great interest - kudos to Pete on the diagnostic work and to everyone else who has chimed in and added their experienced opinion... and

I must have gotten a hold of the same batch of VSP brand plugs as well, and purchased from the same member. 20.5 volts. installed last weekend and no glow. at first i thought my problems were with the slight use of anti sieze i put on the threads, but now im thinking otherwise.

And the plot thickens! E-mail sent - curious to know more details about your situation and experiences as last I heard they worked out great for you!

 

[Joe Egolf]

Got my old glow plugs out of the glove box they read: ND japan 067100-1350 8,5v on 3 and #4 reads japan pt104 8.5n 6n as far as i can decipher it. They look clean and are not burnt out. I put in 4 NEW glow plugs a while back ATC pt104 19850-68030.Who is VSP? I have never seen my glow indicator on the dash glow at all. It is wired and clean.

 

[lostmarbles]

.....If in the end there is not a plug that I can find that works right then so be it. ....Pete

Way too earlier to suggest that this plug problem is so widespread that you won't be able to get any plugs to match your controller Pete! (I wouldn't ever consider modifying my controller under similar circumstances.)

The "low-current-draw" fault may even be restricted to "VSP 20.5V plugs" with no other plug-brand or voltage-spec exhibiting similar problems.

Two brands I've used that I can vouch have performed faultlessly with my controller are HKT and Nippondenso (with the ND plugs being what Toyota usually supplies). ... Although manufacturing methods are always changing so who knows whether or not their current-draws may have changed?

And if you can't buy locally ... there are heaps of Internet vendors and the small size of a plug-package means shipping is not an obstacle.

..Joe and Fatdiesel let us know if what you find out! Are you guys both running 20.5V plugs on a 2b? ..Pete

I believe Joe's BJ42 is a 12V manual-glow set-up (with glow controller) so on that basis he should be running 8.5V plugs.

Have been in close contact with Pete and been following this thread with great interest - kudos to Pete on the diagnostic work and to everyone else who has chimed in and added their experienced opinion... and

And the plot thickens! E-mail sent - curious to know more details about your situation and experiences as last I heard they worked out great for you!

The only time I react (seeking redress) from a vendor is when I think the problem I've experienced was somehow the vendor's fault.

This plug situation doesn't suggest anything negative about vendor or manufacturer in my opinion. (IMO - These old cruisers are "quirky" and a plug that fails to glow the controller in one of these vehicles may still work fine in every other application it is used in.) Edit: What other applications? I'm talking nonsense here! The specifications of these plugs here should specifically match your truck and its glow controller. In other words, the same part-numbered plug shouldn't be in use in any non-Toyota vehicle or even in any other 24V Toyota truck that doesn't have that very same pre-heat system. The manufacturer has no excuses available to them to let them off-the-hook!

 

[DieselLover]

lostmarbles, I'm very much with you. It's clear the plugs glow bright and hot. And this issue would never matter to or affect someone NOT utilizing a glow controller - they wouldn't know or care! The plugs would do their job in the proper amount of time , period. End of story! Any issue or problem seems to only affect the glow controller - not the functionality of the product, so-to-speak.

With that said, it is extremely important to me that the product perform to the user's expectations. I would be just as concerned as Pete is if the roles were reversed - I'd want my glow controller to glow too! The problem is there are so many variables as to why a glow controller won't glow, even with new plugs. I feel like Pete has done a fantastic job of systematically trying to eliminate each variable. I'm not sure what else he can do or try. It's obvious his old plugs work and the glow controller glows when using them. He is the first person I've heard anything of the like from, so to be honest, I was a little skeptical when he said he thought they were bad. Let's face it: electrical stuff can be a pain and problems can be traced back to many different things. Who knows what could be to blame! But luckily, Pete had the patience, the skills, and the tools to be able to systematically narrow things down quite a bit.... And sans all of the investigative "detective" work Pete has done, I would be a little hesitant to just rule everything else out and just say "must be bad plugs!"....know what I mean??

So I am interested to know if:

a) this particular batch of 20.5v VSPs are a little "off" in some way....

or

b) if all of VSP's 20.5v plugs are "off" in some way just enough to cause this problem....

or

c) if the plugs are perfectly fine, yet the "quirkiness" of these old beasts (as you say) and the glow system with glow controllers is to blame....maybe just too finicky with what kind of plug(s) or parameters they require?

I have just received a fresh order of plugs, and am interested in checking something. Now, I have no way of knowing when they were actually produced - and the ones I received this time could actually be "one-in-the-same" as the last ones I sent to Pete and fatdiesel....I have no way of knowing when they were produced and if they were all produced together and to the same specs or not. BUT, it has been Pete's theory all along that the resistance measures of the plugs cold, and particularly, the difference between his NDs and the VSPs, are a crucial part of the equation. I would be interested to measure and see what the other 20.5v VSP plugs I have here show in terms of resistance, comparatively to both the VSPs (and NDs) he has - What do you think Pete?? Truthfully, I wish he were here with his truck and I could toss a set of these in and see first hand!

 

[lostmarbles]

lostmarbles, I'm very ...........................................n and see first hand!

Yep. I'm as puzzled as you are DieselLover. And unfortunately I can't really offer any suggestions on what you should do. (I certainly admire your customer-service!)

If I was Pete I would simply order one or two plug-sets (different brands) from other vendors on the Internet and experiment with them all. I'm pretty sure his problem would be solved easily this way. (And we could all learn from the results - particularly those of us running "glow controllers".)

I've participated in some threads where we have never learned exactly why plugs were repeatedly exploding. So "glowplug problem solving" can certainly be frustrating! And like you, I've often wanted to see the vehicle in front of me and work on it together!

All I can say is ... Having my old cruiser run well in stock/OEM state is tremendously rewarding to me. (Far too many people give up on solving issues/problems and choose instead to modify their vehicles with non-OEM stuff to simply get it quickly back into a useable state.) I actually enjoy working on problems like this one that Pete's having! And I see such things as part of the enjoyment of owning an old classic!

On the subject of "cold-resistance readings". This is what I found some time ago with my plugs:



As you can see, my readings are "double" and "triple" what Toyota says they should be. (Hence my advice to ignore "cold resistance readings".)


And here's that meandering thread with that image in case anyone's interested:
https://forum.ih8mud.com/diesel-tec...ting-along-glowplug-injector-replacement.html

 

[peteinjp]

DL- I suspect that you'll find all the 20.5v plugs from this Vsp will give the same specs in terms of resistance etc. I think most likely the requirements of the glow controller type of system were probably left behind and just a "time to hot at X volts" spec has been put in its place.

BTW Tom I have no expectations for DL beyond what he feels he wants to do. I personally would like to have the opportunity to compare other available plugs in the same way and determine for my sake as well as for everyone else which plugs work as they should with the manual glow system. But I can't really afford to get them as they would add up quick $$-wise and money- like time- well I have other ways I'd like to spend my resources. DL has been very good with the issue as far as I'm concerned and ultimately is not the person who designed them and said "these will work on a 1981 24v 2b."

My personal feeling about these type of situations is case by case and that the vendor and the buyer should work together to find the solution that hurts the least overall as well as one that reflects on the balance of responsibility. Point in case I recently bought what I was told were wheel studs from a german vendor. Well it turned out that they were wheel bolts. It was a simple translation issue and I know that vendor is a quality establishment. However I could not use them and shipping from Japan would negate the cost of returning them. I suggested that we split the difference and that they refund half the money. They agreed. There were other parts in the order that I needed so shipping $$ was not an issue.

In the same order there were duplicate parts that I did not order or need but was charged for. This was clearly not a communication error but a mistake on their part which I was able to verify with my records (email order.) I asked for a full refund and offered to return the product at their expense. They gave me a full refund and let me keep the parts because returning them would negate any profit on their markup. I will not hesitate to do business with this vendor again.

In dealing with this current situation DL has been very attentive and shown concern. I'm pretty sure we'll come to find the most reasonable solution possible and that he will do what he can to be sure that future customers are satisfied with what he sells.

Also I wanted to mention about the resistance readings and the FSM. The picture (stolen from Toms post) is not clear at all in that photo. I pondered this myself- how come they stated a that rating as it is so far off. Well, I suspect that if I could see that pic clearly that I would see the buss bar still attached. Unless I've got this wrong that would mean that the resistance being checked is for all 4 plugs at once. In that case your HKT plug would be kinda close as the .6 figure divided by 4 would give a resistance of 1.5 ohms. Still not dead on. In my case with a resistance of 3ohms on a used plug I come out at .75 for a bank of 4 plugs. The spec is .9.

Also I would like to note that the amperage spec in the 2b engine manual seems incorrect. The manual says to connect the amperage meter to the #4 glowplug lead and turn the key to initiate the glow. The specified reading should be 4-5.5amps for 24v systems and 7.7-10.3 for 12. However I think it should be 4x this much. I think they gave the spec for a single plug. The FSM states that the system should show a resistance of .9ohms and at 20.5v that would result in a draw of almost 23amps- roughly 4 times the stated amperage of up to 5.5.

In the process of checking all this out I came to wonder just how the superglow systems are spec-ed. I'll just say this- I'm satisfied with whatever limitations there are with the manual system. The SG system seems like too much work to diagnose. If I had the wrong plugs I'd be hard pressed to know. The only spec they give for resistance is- continuity. The only other specs are Lighting time and pre-heating time vs water temp. The pre-heating time vs the water temp is verifiable but I can't imagine how the lighting time could be checked as it seems the plug would have to be in the engine where is will be at a particular temp and thus light faster or slower than room temp. One similarity is that the SG system also looks to have the voltage controlled by a resistor. So for those guys I would say the best thing to do is to check the voltage at the bus bar and see if it comes in as it should- since as I have experienced there seems to be a direct relationship between the current draw and the resulting voltage passing by the resistor (which for us manual glow type is the glowing "controller.")

Ok-well this is getting epic. I will end by saying that today for the first time I was able to take my 44 out to the mountains and see what it is all about. I have been preparing the truck for this since I bought it earlier this year. I went with several friends in 2 trucks off onto trails in the Japan Alps. It was an incredible day- beautiful weather with fresh snow as we cleared 800 or so meters. Slipped into 4wd having recently gone though and fixed the engagement system as well- very rewarding as the 44 climbed the steep snow covered trails a sure footed as can be.

Though I have read Tom saying that working on these rigs can be as rewarding as wheeling them I have to respectfully augment that statement and say that wheeling them gives a sense of purpose to the work of fixing and maintaining them and vice versa. Running up a mountain range in a truck without having the appreciation of design and mechanics that can only be gained by getting in there and figuring it all out yourself.... doing it without an empirical understanding a portion of the technology involved would not be even half as rewarding.

Best!

Pete

 

[lostmarbles]

Also I wanted to mention about the resistance readings and the FSM. The picture ..is not clear at all in that photo. ..how come they stated a that rating as it is so far off. Well, I suspect that if I could see that pic clearly that I would see the buss bar still attached. ...that would mean that the resistance being checked is for all 4 plugs at once. In that case your HKT plug would be kinda close as the .6 figure divided by 4 would give a resistance of 1.5 ohms. Still not dead on. In my case with a resistance of 3ohms on a used plug I come out at .75 for a bank of 4 plugs. The spec is .9. .

I think you mean "0.6 divided by 4 is 0.15 ohms" ... but that doesn't really matter anyway Pete.

This is how I was taught to work out parallel resistances back at school: (Alzheimer's helps to bring these memories back more clearly now )



This example proves that if four 0.8 ohm plugs are connected in parallel then their combined resistance would be 0.2 ohms or equivalent to "one quarter of each plugs individual resistance". (Which is probably what you were saying anyway but my concentration sometimes fades he he.)

But then ALL of the above is still largely irrelevant here .... because I have that picture from the FSM in front of me now and it is clear from the original picture that they are testing "just one plug" Pete. (The scanner didn't copy that image well.)

And .... wait for it .......that too is largely irrelevant because I know Toyota FSMs are laden with errors.

I've found before that a pic may not necessarily match the text alongside. And it definitely doesn't in this section of the B/2B FSM dealing with glowplugs:



The image on the left suggests they are measuring "combined current" but the figures on the right are definitely "individual plug current" IMO.

And I see you have noted this discrepancy too by what you say below Pete:

...Also I would like to note that the amperage spec in the 2b engine manual seems incorrect. The manual says to connect the amperage meter to the #4 glowplug lead and turn the key to initiate the glow. The specified reading should be 4-5.5amps for 24v systems and 7.7-10.3 for 12. However I think it should be 4x this much. I think they gave the spec for a single plug...

...The FSM states that the system should show a resistance of .9ohms and at 20.5v that would result in a draw of almost 23amps- roughly 4 times the stated amperage of up to 5.5.....

Here is the scanned FSM image (with the poor quality pic mentioned before where you can't see if the busbar is there or not .. but I'll assure you it is NOT there as I look at the better quality image in the original manual in front of me):



As I say .. the real picture clearly suggests they are measuring individual plug resistance so for my 12V cruiser that 0.2 ohm figure would suggest a plug current of 8.5 divided by 0.2 (since my glow controller drops my 12V battery voltage to around 8.5V) which would give me a figure of 42.5A per plug.

So I think the image SHOULD show the busbar there if it is going to match the text on the right (because that 42.5A figure is very close to my "combined current" figure).

So....if nothing else....we've proven here how careful you have to be when deciding whether to believe what Mr Toyota has written Pete. (Both step 4 on page 8-3 and step 5 on page 8-4 are erroneous in just this one section of our FSM.)

 

[fatdiesel]

the mystery continues...

Just installed 4 brand new Toyota glow plugs today pn# 19850-68040 and i still have the same problem..no glow in the dash controller. (slow glow) I have a 1979 BJ41 24v..each plug is labeled as 20.5v. This is the same problem as the new VSP PT-109 plugs i installed a month earlier. But the plugs that came out of the truck when i bought it were all labeled as 20.5v, but all were different, some with part numbers, some without. My glow controller glowed nice and bright red when these were in. This makes no sense. Could it be that the new plugs manufactured today for the 24v are in some way different??? Has anyone bought new plugs for a 24v 2B recently??

 

[lostmarbles]

Just installed 4 brand new Toyota glow plugs today pn# 19850-68040 and i still have the same problem..no glow in the dash controller. (slow glow) I have a 1979 BJ41 24v..each plug is labeled as 20.5v. This is the same problem as the new VSP PT-109 plugs i installed a month earlier. But the plugs that came out of the truck when i bought it were all labeled as 20.5v, but all were different, some with part numbers, some without. My glow controller glowed nice and bright red when these were in. This makes no sense. Could it be that the new plugs manufactured today for the 24v are in some way different??? Has anyone bought new plugs for a 24v 2B recently??

Just an idea here (.... if you're unsuccessful in trying different brands of 20.5V plugs ... or if you feel you want to try a different tack).

If one brand of 20.5V plugs are drawing too little current to glow the controller properly, perhaps you should try their 19V plugs.

For instance HKT make a PT94 plug that is rated at 19V and the only different dimension (compared to their PT109 20.5V plug) is a 1mm shorter tip. (So there is negligible dimensional difference really.)

Cheers
Tom

PS. I understand these 19V plugs were used on some 24V non-landcruiser B-engines. And because 19V is less than 10% different from 20.5V - I doubt there would be much likelihood of burning them out.

Edit: Did some double-checking and found that 19850-56010 19V plugs were indeed used on a 24V B-engined BJ40. (From February 1974 to October 1974.)

But ..... the 20.5V plug is classified as "Quick Type" and the 19V plug is not .... so that may mean that the 19V won't supply the extra current we want anyway

20.5V plug (Quick Type) = Toyota 19850-68040 = Bosch GPT207 = HKT PT109 = NGK Y178T = Champion CH122

19V plug (ordinary) = Toyota 19850-56010 = Bosch GPT204 = HKT PT94 = NGK Y178 = Champion CH120