Help with cooling FJ60 (1 Viewer)

[workingdog]

Georg at Valley Hybrids put a 5.3l/4L60 in my 84 FJ60 and just for fun I had him put a Mangusen blower on it. I don't push it hard, I rarely get above 0 psi. I just got used to that kind of throttle response from modern diesel pickups and - what the hell.

Originally I had some trouble getting the cooling system to keep from overheating until I rigged the overflow from the radiator cap to the expansion tank. When the radiator cap would release, coolant would escape and air would get into the system which over time accumulated. Vortecs really hate air in the system.

It has been running fine since them. 199 to 203 degrees. Over the weekend, I flat towed my FJ40 from Santa Rosa to 4x4 Labs in Grass Valley. I had already pulled the engine, so it was just a rolling chassis. On I80 past Sacramento I noticed it was running at 208 and as soon as I started the climb to Placerville the temperature climbed to 213/215. I tried really hard to take it easy on the throttle, but it didn't matter how easy I was, on any hill the temp would climb and then drop on each flat or down hill. It hit 217/220 at it's highest as I climbed up to Grass Valley.

Is this simply a case of not having enough cooling capacity in my radiator? Or is there something else that could be going on.

Peter

 

[Rambrush]

Well without pictures it is hard to look at what you have.
Do you have a great fan shroud? Auto trans cooler? AC condenser up there also? Power Steering cooler?
What pulley is on the water pump? standard size and not under driven? is the convertor locking up?

 

[rusty_tlc]

Did you re-core/flush the radiator as part of the engine swap? The radiator for the 2F is friken huge compared to what GM put on a stock engine of higher displacement. If it is clean you should have no problems keeping your engine cool.

FYI if this happens again crank the heater (front and rear) to the hottest setting and run the fans at high. It will cook you in the cab but the engine temp should drop.

 

[workingdog]

Thanks for responses.

I've uploaded pictures. Kind of hard to see what's going on in there. PS cooling is done inline with these cylindrical, finned cooling units underneath. I believe, and I may be wrong, the AC cooler is on the outside, the radiator is on the inside and there is a small thin cooling unit in between that I think is for the blower. It's hidden under the black shroud between the AC and radiator. The magnusen uses liquid to cool the blower (and the air coming in) rather than a traditional inter cooler. It's thinner and smaller than the shroud covering it and there's lots of room for air flow around it in addition to through it.

Hard to see the water pump in these pictures, but I can try to measure one of the pulleys if that helps. But at freeway speeds I was assume the shroud would have no effect.

Thanks rusty_tlc for that, I'm going to take that exact run again next week with a utility trailer and a 5.7/NV4500 in it, so I should experience the same thing.

 

[ARCTICMUTT]

Have you verified the accuracy of the temp gauge?

 

[workingdog]

Yes, I have a OBD II digital gauge monitoring the PCMs temp measurement and I've got a mechanical gauge to a separate sensor. They are generally in agreement although the mechanical gauge tends to lag the OBD II number by 3 to 8 degress - until it gets really hot, then they agree.

 

[Fast Eddy]

Do you have any pics of the cooling fins? There is a wide variation of the packing of cooling fins. I bought one for my tow rig once and after seeing the double-the-price stock piece, I returned the other one. There were less than half the density of cooling fins in the cheaper one.

 

[workingdog]

Here's a picture. There are two and they are out of the way enough I don't think they are contributing to the problem.

 

[Fast Eddy]

No not that. This:

 

[workingdog]

I'll see if I can get my camera in there for the radiator.

As to lock up, I have a really hard time telling when the 4l60 is locked up and when it isn't. If anyone knows a way to get that info from the PCM/TCM I'd love to know it, my digital OBD II gauge can't get it.

 

[Rambrush]

One thing that I see is the fan is not quite far enough towards the radiator in my opinion. You are correct the shroud does not have much affect on cooling at speed its the slow crawl that the fan has to pull air through the radiator. That seems to be the issue.

 

[workingdog]

My problem isn't at a crawl, it's towing at freeway speeds.

 

[Kurtis]

That doesn't seem like a problem to me. My 2006 2500hd would hit 220-230 on the mountain grades in the AZ heat. Granted that was with 10k behind it and A/C blasting but Unless your over 235 I wouldn't be to concerned. It sits around 205 in any condition other than hard towing. Once it hit 225-230 it would hold that temp however for as long as the hill continued. It wouldn't go over that.

 

[Rambrush]

Thanks I knew that and got off track. Time to go crawl back in my hole.

My problem isn't at a crawl, it's towing at freeway speeds.

 

[workingdog]

"Unless your over 235 I wouldn't be to concerned".

Well that hadn't occurred to me that the operating temperature range would be so large.. I had assume that anything above the boiling point of water was a problem. But I searched around and you are right. I could not find anything official about the operating temperature of a Vortec, but I did find this about the boiling point of coolant - which is considerably higher than I imagined.

"The pressure cap on a cooling system is the key to raising the boiling point of the 50/50 mix of antifreeze and distilled water. For every pound of pressure cap rating the boiling of point of the above mixture raises 3 degrees. If you had plain water in your cooling system with a 15 pound pressure cap the water would boil @ 257 degrees. If you had a 50/50 mix of antifreeze and water the coolant would boil @ 265 degrees with a 15 pound cap. The boiling point would raise to 270 degrees if you had a 60% antifreeze mixture with a 15 pound cap. If you had a 70% mixture the boiling point would raise to 276 drgrees.

Don't be fooled by the old wives tail that by adding a richer antifreeze mixture will keep the complete system cooler. In fact it works just the opposite. As you know pure antifreeze has a higher viscosity rating than plain distilled water. * The higher the antifreeze mixture percentage its ability to adsorb heat from the engine goes down. *The higher the antifreeze mixture percentage also retards the radiator's ability to get rid of the coolant heat.

Race cars use pure water in their cooling systems because it adsorbs heat from the engine and gets rid if it in the radiator *better than any antifreeze mixture.

It's to your cooling systems advantage to mix your pure antifreeze/water mixture to protect the engine from freezing 10 degrees lower than last years coldest day last winter."

I assume that as long as the coolant isn't boiling, engine if fine.

Peter

 

[workingdog]

I also found this, for future searchers.

Have you ever tried to find what proper coolant temperature is for most automotive engines? There are a lot of people who think they know, but it is difficult to find specifics, even in textbooks. We know we want the intake air to be as cold as possible (for best power) because cold air is denser (there are more oxygen atoms per cubic foot). The coolant temperature, however, is a different matter. The internal combustion engine changes chemical energy stored in gasoline into heat energy that is focused on the piston tops. If the cylinder heads and engine block are too cold, they will absorb much of the combustion heat before it can be used to push the piston down the cylinder. If the engine gets too hot, engine lubricants can break down, as well as overheating of the intake charge can lead to detonation, etc.

It turns out that coolant (usually a 50/50 mixture of coolant and water) has some fantastic properties that are ideal for use in engines. With a properly pressurized cooling system, coolant will not freeze until –30°F, and it won’t boil until +270°F (new oils don’t start to break down until well over 270°F). With these characteristics, engine designers have decided that engines should operate at approximately 210-215°F. Why, you ask? Well, it has to do with operating the engine at a high enough temperature to boil water out of the oil after the engine is cold started. If you have dew on the grass, it is certain that you have water in your oil, as the crankcase is open to atmospheric pressure! You can either remove the water by draining it out the bottom of the oil pan (remember the oil floats on water) or run the engine long enough and hot enough to boil the water out of the lubrication system. Years ago, coolants weren’t as sophisticated and engines were run at 165-180F, but the oil was changed every 1000 miles or so. That’s why many old timers think engines should run at 165-180F. Have you ever noticed that Ford doesn’t put temperature marks on their gauges? They just mark C for cold and H for hot and write “normal” through the center. If you hook up a scan tool to a GM, you will often find that the gauge reads much lower than the coolant temp sensor. That is because they know most drivers don’t understand how hot an engine should run.

So what does this have to do with camshafts? Many enthusiasts erroneously think that the colder their engine runs the better! If they are not running the engine hot enough to boil the water out of the oil, the oil becomes contaminated and the lifter/cam lobe interface is the highest load point in the engine. Engines running too cool can contribute significantly to camshaft and lifter failure. Think about it: What good does it do to use the most expensive synthetic oil and then run the engine so cold that it is contaminated by water vapor??!! Another point, piston manufacturers’ piston-to-wall clearance recommendations assume you will be running the fully warmed engine at 200°+F. Run the engine too cold, and you could see some scuffed pistons because the cylinders had not expanded enough to provide clearance.

If your engine will only run its best at the drag strip with the engine at 165°F, you probably have too cold of a spark plug heat range and you are probably jetted way too rich! If you keep the engine hot (not the intake charge), you will be using more of the heat energy in the gasoline to make power instead of just heating up your block. It does take “tuning know-how” to run an engine at 200-210°F, but you might be surprised how well and how long it runs when you do!! One final point - running a computer managed engine at 165°F compared to the factory 210°F will often cost you as much as 4 MPG. The reason for this is that the computer thinks that the engine is not off the “choke cycle” and it is still putting out a rich mixture! Check the science on this and don’t pay attention to the “old wives tales” of the past. Materials and lubricants are much better and different today than they were in the past!!

 

[Elbert]

fan clutch engaging and working properly.? I just don't think the 60 has enough radiator capacity (exposed square inches of the radiator core) to be an effective tow rig...add the supercharger which is pushing the cooling system even more and then towing with it.

I've got a 07 2500HD 6.0 gas pickup... I haul my 60 around on it with a dual axle metal deck trailer that all total somewhere around 9K or so.... truck sits around 200-205 ac on or ac off...regardless of conditions...that's the GM stock gauge. But the pickup has a radiator core thats a good bit larger than the 60. I belive the 6.0 engine has something like a 187F thermostat.

I don't tow stuff with my 60, but with the ac on it and on the hwy its sitting around 200 or 205F and under a good load or aggressive offroad stuff it will get up around 215F. 5.7 vortec

I think its pushing a 60 to tow with it and use a supercharger...it if does not boil over and does not go north of 220F I guess you are ok, but that's gettingon the edge.

 

[Kurtis]

According to the actual GM manual it says normal temp is up to 250 degrees Fahrenheit when pulling a load. 260 is when you should be concerned.

 

[workingdog]

Thanks Kurtis. That's the confirmation I was looking for.

Peter