V-8 Conversion Cooling

[Elbert]

One note for those who are swapping V-8.

Its been my experience that when you drain the coolant out of the V-8 and you go back to fill it up and to bleed the system, that its really a pain in the but to get the air out of the system and to get the thermostat to function properly initially.

You can have the radiator full of coolant....and the engine is just about empty...and you'll get some nice high temps and the thermostat will not open..big air pockets in the engine.

Solution.....fill radiator up to max level, remove water neck at engine intake, fill engine to max level of coolant, replace water neck at intake and proceed to bleed the system. Let engien run a while with the radiator cap open and fill as necessary until thermostat opens and then top off the coolant. Drive around for a while, let truck sit overnight or for an extended period...top off coolant and you're ready to go.

If you have to drain the coolant from the engine...the above process works for me...as its "hell" to deal with the huge air pocket in the engine unless you fill coolant from the intake water neck opening.

 

[OyajiJon]

Hey Elbert, I answered your PM. Let me know if you have any more questions. I think the PM will be clear as mud, though.

-Jon

 

[ntsqd]

Looking good!!!

A trick that I've used for years with good success is to drill an ~1/8" hole in the flange of the t-stat. It will bleed a little coolant when cold, that is why so small, but it will also bleed out any air trapped under the t-stat. I got the idea from the OE t-stats used on most Asian imports. They have a little thingabob that partly plugs the hole, but I've not ever felt like I needed something like it. With Ford small blocks I orient the hole to be at the top of the t-stat. With a GM maybe at the front (due to the tilt of the engine), but I don't think it matters all that much.

 

[Elbert]

yea...

I thinik on the small block swaps and the general configuration of the FJ60 engine setup...its pain to bleed the system. I have seen the type of thermostat you are referring too. Has a small hole with what appears to be a small metal ball serves some purpose...maybe it allows flow in only one direction.

But if the engine is basically dry....the normal "bleed" process is not going to work and so see above to what I've resorted too. We ended up pouring at least 3/4 of a gallon into the engine from the water neck openign on the intake manifold.

My engine sits as high as possilbe under the hood (just barely clears the hood)...radiator in stock location.

I'm liking the shroud...I could kick myself in the @$$ as to why I did not look at this in greater detail when I first swapped engines.. Well I'm posting all of this so it may help others, as I've been helped numerous times by the info on the board.

 

[Elbert]

Jon,

what radiator are you using? Do you plan on getting your A/C to work. Looks like from the pics your compressor is not connected to the hoses?

I headed to get A/C working and integrate the GM stock type alternator.

 

[FJ40 TOOLMAN]

Try this tool to fill your cooling system Lisle 24610 Spill-Free funnel probably does not work sold a lot of this and never got one back

 

[Elbert]

Hey Elbert, I answered your PM. Let me know if you have any more questions. I think the PM will be clear as mud, though.

-Jon

got it..

 

[OyajiJon]

Hey Elbert,

My AC isn't hooked up yet, but it shouldn't take too much effort. Obviously, custom hoses to mate the GM compressor to the Toyota system are a must. I haven't been too worried about it since it's always cold and gloomy here. The compressor that came on the engine had a locked up clutch, but I have another in a box for when I get around to it.

On the radiator, it was a universal aluminum one that Ron ordered. I'll see if I can get a source and part number. He made mounting pads for it so that I can drill 4 holes in the top lip of a new one and toss it in there. It's a real trick set up, but I can't take credit for any of it. Custom Cruisers in Gilroy, CA did it. I'm a fabrication amateur, so I trusted the pros to take care of things that would leave me stranded or kill someone when it comes loose. I'm learning, but welding isn't my thing...yet...

That said, I'm quite confident I could fix anything, mechanically, on this thing given the appropriate amount of time.

 

[FJ40 TOOLMAN]

The radiator looks good .I think custom cruisers is on the right for cooling.I think it was the same Cruiser I seen in the shop about three weeks ago.

 

[rover67]

Is there space for airflow from the edges of the radiator to the center where the fan is? It looks like the shroud fits really close..

nice work on the shroud though, I dig it.

 

[Elbert]

more shots of it installed. Note the burrito tray It was kind of an accident that it turnied into one, but it works really really well. The upper hose was from Napa, PN 8991 and it fits really well. I kind of had to squeeze it on the stock radiator inlet, but it works.

Sent you a PM on this question I had...

But I think your pics have answered it in part. Was wondering if your fan shroud setup totally captured teh radiaotor fan blades. I see by the pics that it does not. Mine does and I wonder if that's causing an issue with air flow across my radiator (lack of air flow) and thus impacting the fan clutch ability to work properly.

Wondering if I need to trim fan shroud depth? to maybe expose 25 to 50% of the fan blades.

At present fan clutch does not engage uniformerly...(seem to have a mind of tis own)...when it does engage it does cool down.

Saw 220F on the trail and that's too hot.

see post 94 for my pics showing shroud and your posts earlier on this same thread.

Debating on if I need to remove shroud and trim the depth of the portion covering the fan blades.

Thaoughts on that?

see post 94 for my pics on present setup.

 

[Kurtis]

Are you using an electric temp gauge or mechanical?

 

[Elbert]

mechanical autometer temp gauge. Also I know the parts are correct (GM Fan and Fan clutch).

I'm wondering at this point if I need to modify the fan shroud to allow exposure of the fan blades to some extent.

prior testing with no shroud...the fan and fan clutch really worked as I could hear them come on. Now that shroud is on I don't see tha that the clutch is acting as aggressive. I can't say right not that that shroud is my problem but it would appear that it might be, as nothing else comes to mind other than the fan clutch may be defective.

 

[Kurtis]

The mechanical gauge is up to 20 degrees off. I bet your not even seeing 200 degrees under there.

Hook up a scanner when your driving or switch to an electric gauge. Mine was way off. When I installed my fan shroud I was actually seeing higher temperatures than before the shroud with the mechanical gauge but it was just the hot air blowing off themanifolds warming up the the sensor. When I installed the shroud it channeled the air more over the engine instead of out the sides and it warms the pos gauge up. The old electrical fan set up you had wouldn't move that kinda air over the engine I really doubt it you would get that type of issue before.

 

[Elbert]

Kurtis,

as I recall off-hand the temp sender to feed the guage is in the drivers side cylinder head, the temp sender that feeds the ECM is in the intake manidold. Generally speaking on SBC I expect to see about 10 degrees differnece between these two...and that in my mind is dure to the location of the sensor...the intake being cooler than the cylinder head. In other projects of mine I've noticed the same. I noticed roughly the same thing on a TBI 350. Steel cylinder heads aluminium intake. Its been my experience that mechanical gauges are more accurate than the electric versions.

At this point in time I think I will be modifing the fan shroud to expose a portion of the fan blades...I hate to even do that as my friend did a great job on the shroud, but its looking like a portion of the fan blades need to be expoased on the engine side of the fan shroud.

Still looking for comments or experience in this area.

To correct a previous statement I made...on my K2500 suburban..the radiaotr fan blades do indeed stick out past the shroud for about an inch or 1.5 inches or so. Aslo noted that other factory setups have the fan blades exposed to some degree. I've not been able to look at a 99 GM Pickup or SUV but I'm almost sure that on those trucks...the fan blades are also exposed to some degree.

 

[Kurtis]

The sensor is so close to the manifold its like a blow dryer running right at the sensor.
I did a test before and after the shroud. The ECM temp read lower after installing the the shroud the mechanical sensor red 5-10 degrees higher after the shroud. It is defiantly not close to being accurate.

I have really flogged this thing in 111 degree heat and 107 degree heat on 6-7% grades rolling on 35s and stock gears and it won't heat up. I left 3/4" of the fans blade showing. Wheeling it runs especially nice and cool even in the heat. I thought with the a/c I might have ended up needing a better radiator but it wasn't the case.

That being said the hottest I have seen in these temps with the mechanical gauge is 215 and that is 75mph 3rd gear 107 at 6% grade fully loaded. Another indicator of its inaccuracy is watching when the thermostat opens up. It is a stock 192 thermostat and watching the mechanical gauge it won't open until 205.

 

[ntsqd]

My job partly involves the Instrumentation of engines and turbochargers in a testing environment. I consider aftermarket automotive gauges to be "dash jewelry." That seems to offend some people who've consumed the gauge marketing Kool-Aid, but it can't be helped.

There are two factors in considering accuracy. Actual number vs. the sensor/gauge reading; and how well the measuring system repeats readings. If you want repeatable real accuracy you need to look into industrial sensing parts. Even those will have drift over time as well as a tolerance window for their repetition and their accuracy, but unless you are data-logging many times per second and doing this year-in and year-out I doubt that you'd notice the difference.

When I see a 10* disagreement between factory gauges and "dash jewelry" I consider that to be the same reading. Until the gauge maker publishes accuracy and repeatability specs they're all suspect numbers. OE sensors for EFI systems are necessarily pretty good. I'll take a reading from one of those over any other normal automotive gauge.

Another thing to keep in mind is the Heisenberg Uncertainty Principle. Essentially the attempt to measure something causes a very small change in the something, so you can never get an absolutely accurate measurement.

All of this is a long way of saying don't put too much faith in a particular reading based solely on where it is reading from. There are way too many other variables involved.

-*-*-*-

I just popped the hood on that pinnacle of modern engineering (note: sarcasm), my '91 1/2t 4WD Suburban w/ 5.7l TBI. It's clutch fan blades have their rear-most <1/3 of their depth exposed to the rear of the shroud.

 

[Elbert]

Is there space for airflow from the edges of the radiator to the center where the fan is? It looks like the shroud fits really close..

nice work on the shroud though, I dig it.

there is some space along the flat edge of the shroud around the corners. Since its going to be a royoal pain in the @$$ to get the shroud off, when I do take it off to modify the coverage of the fan blades . I'm thinking about adding some 1/2inch or 1 inch square tubing around the edges of the shroud to basically extend the shroud toward teh engine, therebye allowing a greater gap between the radiator core and the shroud. Which I assume would promote air flow through the radiator.

 

[Elbert]

My job partly involves the Instrumentation of engines and turbochargers in a testing environment. I consider aftermarket automotive gauges to be "dash jewelry." That seems to offend some people who've consumed the gauge marketing Kool-Aid, but it can't be helped.

There are two factors in considering accuracy. Actual number vs. the sensor/gauge reading; and how well the measuring system repeats readings. If you want repeatable real accuracy you need to look into industrial sensing parts. Even those will have drift over time as well as a tolerance window for their repetition and their accuracy, but unless you are data-logging many times per second and doing this year-in and year-out I doubt that you'd notice the difference.

When I see a 10* disagreement between factory gauges and "dash jewelry" I consider that to be the same reading. Until the gauge maker publishes accuracy and repeatability specs they're all suspect numbers. OE sensors for EFI systems are necessarily pretty good. I'll take a reading from one of those over any other normal automotive gauge.

Another thing to keep in mind is the Heisenberg Uncertainty Principle. Essentially the attempt to measure something causes a very small change in the something, so you can never get an absolutely accurate measurement.

All of this is a long way of saying don't put too much faith in a particular reading based solely on where it is reading from. There are way too many other variables involved.

-*-*-*-

I just popped the hood on that pinnacle of modern engineering (note: sarcasm), my '91 1/2t 4WD Suburban w/ 5.7l TBI. It's clutch fan blades have their rear-most <1/3 of their depth exposed to the rear of the shroud.

yeah..I'm not trying to baseline anything or state with any accuracey ... I have noted a differnece between what the PCM scanner tells me is the engine temp and what the autometer gauge displays as the temp. I can't say either is more accurate than the other. I do know that the sensors are in different locations. I prefer a mechanical aftermarket temp gauge over a aftermarket electronic version.

I do have a scan tool that can "view" live data, so I'll look at that later once I've modifed the shroud. I do know traditionally GM has used the port in the drivers side cylinder head for temp sensors .. at least back into the 60's, well before PCM and ECM engine controls.

On the vortec 5.7 the PCM temp sensor is right up on the intake near the water neck.

I'm sure there are many issues that go along with the word "accurate"... my prefernece for no-stock gauges is mechanical. I can't say one gauge is more accurate than the other...what I can say is they are measuring temps from different locations on the engine. So maybe my statement above may be only in "my mind" about the accuracey...I was generally referring to aftermarket gauges comparing mechanical to electric. Maybe a better statment would be that in my view I trust the mechancial gauge over the electric, but that's just my view. I've also see plenty of OEM guages that I don't trust...espically ones that seem to never to move.

Bottom line on my recent comments... I think at presnt my truck is runnig too hot, I did not have my scanner out on the trail so I don't know what the PCM was reading.

Appreciate the feedback on the fan blades on the GM machine.

 

[Kurtis]

I guess what I'm getting at is you might want to measure your actual air temp coming off the radiator with an infrared thermometer and compare that to what the fan clutch is supposed to engage at. When I looked this up (all this information is from random sites on the net so not the most trust worthy but makes sense) it seems like most stated that the fan clutch would engage at 200-210 degrees actual engine temperature taken off the ecm. (slightly lower real air temperature190-200 air temp) With a lot of people saying 206 on a scan gauge. This makes sense seeing that your oem thermostat is set at 195 it wouldn't make any sense for the fan to engage before the engine was warmed.