Cooling Issues... What have I missed?

[arizona78]

I have a 1978 FJ40. Stock 2f, 74K. Recently passed emissions with flying colors. New radiator, waterpump, fan clutch, OEM thermostat (with appropriate gaskets). When I put in the thermostat, I flushed the system with a Prestone kit and filled the system 50/50 distilled water/coolant. After about 15-20min of driving, temp gauge is riding the upper hash mark of the middle range. \ | | / Driving 65mph down the highway for extended periods will push it just a little higher. At stoplights and lowspeed driving, fan clutch is engaging. New temp sender didn't make a difference. I tried putting a termocouple in the heater line just after is comes out of the bock, about 4 inches from temp sender. Opened the heater valve to ensure flow. Looks like the temp is 210 to 220 degrees F, so I don't think the gauge is off. What is going on??? Can the radiator be clogged already? Do I need flush the system again, this time will chemicals? When I flushed the first time, I didn't see any sediment come out, and I did open up the block drain. This is driving me crazy!!!

 

[Bailey]

Might be an air pocket in system. Try to top off the fluids again with the front end on a ramp (or curb) and make sure your heater valves are open.

 

[Steel]

Try running it without the thermostat.

 

[Landpimp]

no don't do that.

Try running it without the thermostat.

 

[Landpimp]

whats a termocouple?

is your timing set correctly? if its retarded(or possibly advanced to far) it can cause overheating. is you dizzy elec or points?

possible as Baily says , an air pocket, leave the cap off, park the 40 with its nose up higher than the rear(the higher the better) and let the system burb the air, never had this problem in a 40 but on a 60-2 it can be...........but worth a shot.

Question, is it overheating like it was before you replaced all the cooling system? or why did you replace everything?

it would be very nice to have a non contact thermometer........man oh man that has saved me some major headaches over the years. But in lue of that, how hot to the touch is the upper rad hose? can you hold it with your hand for more than a few seconds(with out discomfort)? if so its not running hot.

When I shoot the temps on my cruiser I look at the lower t-stat housing(not the top) or the head(as head temps are 10deg higher than t-stat)

John

 

[desertdude]

I run full strenght coolant ( not a water mix) - how are your hoses, fan shroud? Could the thermostat be faulty? Check it in boiling water and watch it work

 

[TonkaC]

I use the extended life antifreeze in mine. Up north here I use it because it will give better cold performance and it does cool better. If you try everything else you might want to try that. Mine with a SBC runs at 170 all the time, never goes above. I would also check the thermestat to see if it is working correctly. Toss it into a pot of water and take the temp up, see when it pops.

Chris

 

[arizona78]

Termocouple = Thermocouple, sorry about the spelling. It's an electronic thermometer. The one I have plugs into an inexpensive electronic multimeter from Sears. Supposed to be able to read -4 to 1700 F.

Electronic distributor, no points. If the distributor was too far advanced or retarded, wouldn't that have additional symptoms???

The radiator, water pump, fan clutch were replaced about 2 months before I bought the vehicle by the PO. I think he may have been chasing the same issue. When I went to replace the thermostat, the housing was empty. So, I put the new one in and it made NO difference on the temps. Flushing the system with the common prestone kit made NO difference.

When I herculined the tub, I took out the heaters. Rear heater lines were full of browish sludge. I flushed out the heater lines and the heater core with a hose until they ran clear.

Top hose on radiator is damn hot to the touch when its fully warmed up. I tried putting a temporary aftermarket gauge in place of the stock one for troubleshooting purposes to rule out the stock gauge, but I couldn't get the aftermarket sending unit to seal properly in place of the stock on. Kept leaking...

 

[1Fine40]

One other thing to check....could be a not great ground on the gauge pod. I had that happen to me. Fix was to remove the gauge pod, clean the contacts really well with steel wool and used a few star washers on the electrical conns. Gauge then read correctly. Although yours does sound like it is getting actual overheating... Anything in front of the radiator??

 

[arizona78]

So, I was finally able to get the aftermarket gauge sender sealed up and working in the stock location. Aftermarket gauge indicates 210 degrees, thermocouple ~215 after warmup and driving for about 20min. So, the stock temp gauge was correct all along...

Now I'm thinking that maybe the flow in the engine is restricted or something. Based on the crud I found in the rear heater lines and the in the coolant overflow reservior, maybe the flow is poor. For the record, it's never overheated or gone above ~215. Just seems like once warmed up it can't get all the heat out...

I bought some Prestone cooling system cleaner. Anyone used this??? Seems like a PITA. Multiple fills and drains... Ideas?

 

[Cruiserdrew]

I'll bet it's a bad radiator. As you said, everything else is new. Pull it out (6 bolts and 2 hoses-easy) and have it flow tested at a radiator shop. If it's a 3 core and not a 4, it's cooling capacity will be marginal so you might consider that as well.

 

[hammerhead]

I agree with landpimp. Doublecheck your timing. It only takes a degree or two off in timing to make a drastic change in temps.

Also remember that modern fuel is crap compared to what we had when cruisers were made. If you have good compression and run a low octane fuel it can show a higher temp.

 

[Landpimp]

retarded timing might or might not have other symptoms, it won't ping, but you wll loose some power(which you wouldnt notice if its been like this sense you got it). advacned might or might not, if too far it should "ping" but it might not if only off a few degs.

215 is hotter than it should be but not killing anything yet. 180-205 is where you want it.

I bet its in your timing.

how about the carb? I think too lean will cause it to run hot.

is the rad "really" new, if the fan clutch OEM?(but on the highway its really not suppose to kick in) T-stat is OEM 190? (I have had one bad new OEM be bad out of the box.....1 out of 10)

I have flushed out what looks like brown poop in a 2F or f cooling system......oddly it didn't effect the temps one way or the other.

water cools better than anti freeze, 50/50 is fine.......100% anti freeze is not something i would do.

One that had me baffled was my 86 fj60 w/100k, never ran hot(all new hoses, t-stat, OEM fan cllutch) But then I had the old stock carb rebuilt......it then started running up to 210(I have a raytech non contact temp meter) on the highway only. The rad looked fine, flushed it out....no diff. What was it? well the new carb was working like it was suppose to and the 18 year old rad just wasnt up to cooling it with the added(like new) power it made...a new rad(Preformance Rad) was the cure, it now ran at 185-195....I did experement with a 180 deg t-stat and that droped it anohter 10 degs, but if your system has other issues or the motor is not causing the problem(ie timeing) a 180 deg t-stat will do nothing for you. I can sit in the 100deg heat, with the AC on and the temp never goes over 195.

also my fj45 with 772f, new FC, new rad, new t-stat, fine around town but after a while it would climb to 205-210 on highway. It never really bothered me much(ok it did) What was it......not sure but it runs NO hotter than 190 now.....what changed, I went from a questionable 75 points dizzy to a fully elec fj60 dizzy, I was always fighting with the points on that 45, timing was always right on(but i had to adjest everytime I messed with the points). Now 190deg tops(even at 100deg doing 70mph), MUCH more power, better MPG. Thats not prolly the problem on yours. But check that timing!

John H

 

[arizona78]

Ok, dug out the timing light. Do all of the vacuum hoses need to be disconnected from the distributor to check / set timing? Haynes manual does not specify.

Radiator is not stock. Looks like it came from CCOT, based on one that I purchased for my now-sold '71 FJ40. Thermostat is 180 degree, Toyota. You may correct me, but I think only 1979 and later had 190 or 195 degree thermostats. Water pump looks like Checker/Shucks/Kragen (whatever happens to be in your neighborhood) special. Can't tell if fan clutch is OEM or not. If it isn't, it looks very similar. Seems engage only after the engine heats up to over 200 degrees. Verified fully transistorized distributor. I have had idle and choke set when I purchased it as the PO had swapped some emissions vacuum lines and screwed up the idle settings. I have since purchased the emmissions manual for 1978 and made sure all of the plumbing is correct. But I bet the mechanic didn't look at the timing... No one around here seems to like working on older vehicles, let alone older import vehicles. Heading to garage now...

 

[Landpimp]

if all is working right, you can leave the vacuume hoses on the dizzy, but to be safe pull em off(if however you pull them off at idle and the idle drops......thats not correct)

also when your checking the timing, suck on the hoses that go to dizzy, the inner one should be advance(and the rpms will go up when you suck on the hose) outer is for high altitude, check this as well, rpms will raise. Now this is for a 79+ with advance/advance, 78 might be advance/retard.......sorry I don't have one of those

you know you want timing set at the BB not the line?

waterpump is not the problem(pretty darn sure) they work or don't and leak or make noise if going bad.

75 I know uses the 180deg t-stat,(thats what I used for an aplication when getting mine) 76-8 might as well, but it really won't make it run hot, so we will rule that out, if it works that all that matters now.

the CCOT rads are suppose to be just fine. ( I run a $99 made in Korea rad in my 66 fj45 w/772f, works fine)

its possible that it might be emissiion related but I kinda doubt it, not sure what part of the system could cause it to run hot


so lets see if the timing is correct or not....I am hoping thats what it is.

Ok, dug out the timing light. Do all of the vacuum hoses need to be disconnected from the distributor to check / set timing? Haynes manual does not specify.

Radiator is not stock. Looks like it came from CCOT, based on one that I purchased for my now-sold '71 FJ40. Thermostat is 180 degree, Toyota. You may correct me, but I think only 1979 and later had 190 or 195 degree thermostats. Water pump looks like Checker/Shucks/Kragen (whatever happens to be in your neighborhood) special. Can't tell if fan clutch is OEM or not. If it isn't, it looks very similar. Seems engage only after the engine heats up to over 200 degrees. Verified fully transistorized distributor. I have had idle and choke set when I purchased it as the PO had swapped some emissions vacuum lines and screwed up the idle settings. I have since purchased the emmissions manual for 1978 and made sure all of the plumbing is correct. But I bet the mechanic didn't look at the timing... No one around here seems to like working on older vehicles, let alone older import vehicles. Heading to garage now...

 

[arizona78]

Timing was/is retarded. The little BB was pretty much completely out of the timing window. I took off the vac lines and verified that there was not vacuum on either of them. You are correct, I have the advance/retard distributor. According to the manual, if the Spark Control system is always on, this can cause overheating. If you're interested, this is how it works:

1) Idle, system is always off.
2) Below 140 degree engine temp, system is always off.
3) Above 140 degrees, throttle open, 1st through 3rd gears, timing retarded.
4) Above 140 degrees, throttle open, 4th gear, timing advanced.

At idle it appears to be working correctly. Of course, nothing really matters until the timing is right...

I'll let you know how it works... Thanks so much for the insight.

 

[Landpimp]

great! hope it runs cooler now,

curious, now does it know its in 4th gear? (to advance timing) I don't know how the 70 emission stuff works, just the 81+ and even then just kinda

might as well test the VSV's while you are at it, should be 1-3 of them on the t-stat housing, those are the sensors that open/close to open/close up the vacuume, should be able to not blow thru(outer to inner, I think) when cold, when warm they should be open.

John

Timing was/is retarded. The little BB was pretty much completely out of the timing window. I took off the vac lines and verified that there was not vacuum on either of them. You are correct, I have the advance/retard distributor. According to the manual, if the Spark Control system is always on, this can cause overheating. If you're interested, this is how it works:

1) Idle, system is always off.
2) Below 140 degree engine temp, system is always off.
3) Above 140 degrees, throttle open, 1st through 3rd gears, timing retarded.
4) Above 140 degrees, throttle open, 4th gear, timing advanced.

At idle it appears to be working correctly. Of course, nothing really matters until the timing is right...

I'll let you know how it works... Thanks so much for the insight.

 

[arizona78]

Well, despite setting the idle speed and timing, that doesn't appear to be the issue. Went right back to 210 when I took it for a spin. I checked the brown BSV for the SC system, and it is open. The system knows it's in 4th gear via a switch on the transmission. In the emmissions manual there is a detailed procedure for checking the distributor, trans switch, and main emmissions vacuum switching box. Checking all of that crap is doable, just a PITA. Especially the trans switch. Well, I guess that's for another weekend. Thanks for all the info. Have a great week.

 

[Torskin]

Since you have done every thing else, it has got to be the Radiator. It maybe new, but then again it could be flawed. Try running the car upto temp then spraying water onto the radiator and see if any water stays on it instead of Evaporating as described in the FAQ at http://www.birfield.com/~ramullen/FAQ/TEXT/00-01.html. Might also check the water pump and see if it is operating correctly.

Just some thoughts

 

[RedGreen]

This thread is extremely interesting to me as I'm having very similar problems with my '78 FJ40, but mine runs perfectly normal until I get onto the hiway. Then it slowly creeps up until it overheats. Same thing, I've replaced radiator (CCoT), water pump (OEM), t-stat, rebuilt fan clutch, rebuilt the whole engine, etc. I even tried removing the t-stat and now it just runs a little cooler before creeping up on the hiway. Once I get off the hiway, the temp comes right back down. The only difference is I don't have any emissions left in mine. (no advance/retard on dist.)

Can a shop tell if the radiator is bad? You're right, shops definitely don't like working on these old trucks. I think they had to pull a guy out of retirement when I asked them to set my mixture/idle on the carb.

Thanks for the thread. I'll keep reading to see if you hit on anything that may also solve my problems.