LS-coupe cooling saga continues :(

[MstangsBware]

Possible the AC compressor is on its way out and causing drag when turned on? Maybe clutch is starting to drag when engaged....While I agree 230* is higher than what I like to see alot of GMs cars are setup that way....

[dville_gt]

Possible the AC compressor is on its way out and causing drag when turned on? Maybe clutch is starting to drag when engaged....While I agree 230* is higher than what I like to see alot of GMs cars are setup that way....

This is something I have thought about more and more. It does feel like the a/c compressor loads the engine a decent amount, but it's only a 5 rib belt and it doesn't slip. I can easily turn the compressor by hand. I've had compressor seize all the way up before and never had an overheating problem up until the time the car wouldn't start due to it being seized.

[dville_gt]

At minimum, cooling system temps will usuall run a minimum of 15 degrees above advertised thermostat temperature. 160 will usually run in the 175-180 range, 195 will be in the 210 range. Gm cars stock are setup to run in the 220-225 range on a lot of vehicles. From v8 camaros to grandma's 3800 buick.

thermo is a 187 degree unit, so around 200 would be explainable, 230 with the fans programmed to be on all the time (under 35mph) doesn't really make sense.

[turbostang]

There are two pieces of advice in this thread that I would do FIRST, they are the cheapest and quickest.

First, as Paul said - I'd be doing a block test, especially considering knowing this motor has been leaned out pretty good on more than one occasion. You can not fool a block test. You can fool a leakdown and/or compression test.

Second, As David said, I'd be changing thermostats down to the 165.


Between those two things, I bet you'll find your problem and for me the 50-60$ invested is well worth my time wasted on the other stuff if they don't work.

..and before anyone asks,yes, I do agree - the air dams and routing are important, but I don't think it's the problem in THIS car.

[dville_gt]

Quick question:

The radiator I bought didn't come with a radiator cap. Turns out the f-body cap fits perfectly and seems to seal up to this radiator just like it did the stock radiator (this is a new OEM cap btw).

Here is where it gets a little interesting. When I add water to the bleeder in the upper radiator hose it eventually ends up in the overflow and the level in the upper lowers. For example I left the bleeder out last night and topped it off. Came out this morning and it was very low, but my overflow was very full. So again, I topped off the bleeder and I am sure when I get home today from work the overflow will be full and the upper will be low.

My question, I know that the radiator cap allows coolant to be expelled to the overflow when system pressure is greater than 18psi (with this cap), and allows coolant to be brought back from the expansion tank as the system cools.

With the motor cool no water from the cooling system should be able to make it's way past the radiator cap, correct?

I am going to contact the manufacturer and see what cap they suggest. Is it possible that this cap is simply not sealing the radiator from the expansion tank and allowing the water level in the upper hose to fall down to the level of the filler neck thus introducing air into the system?

[kingjason]

I stole this from pirate just in case you want to try the different fans. They are also cheap but get ready to do a little wiring they pull some juice on high.

Originally posted by randii
The Taurus fan works well, but the Mustang folks have been using the Mark VIII for quite some time: http://www.geocities.com/smithmonte/...rkVIII_Fan.htm
...they claim it has the best airflow.

For severe cooling needs, the electric fan from the Lincoln Mark VIII provides the greatest airflow. The part number is F8LH 8C607 AA -- I got mine from the junkyard for $15, but they are available new for just over a grand. Fan diameter is 18" and the fan blades are optimized for low noise but high flow. Outer dimensions of this fan are 22"W x 18.5"H x 6.25"D.

94 and 95 Taurus fans work, as do the SN95 Mustang fans and late-model low-hood T-birds. Pontiac Fieros have pretty good 2 speed electric fans, as well.

Randii

mark VIII and 3.8 taurus are the same part #, same fan

Heres the link and some decent info.

http://www.pirate4x4.com/forum/archive/index.php/t-120931.html

[shumpertdavid]

thermo is a 187 degree unit, so around 200 would be explainable, 230 with the fans programmed to be on all the time (under 35mph) doesn't really make sense.

I haven't had to replace many of the thermostat's that are located in the lower hose area like the LS stuff. The few that I have done always seem to have a lower opening temp then the ones more commonly located in the upper hose areas. I assume that even though the thermostat has a lower rating the engine temps should normally be in the 210-220 range, as this is the normal temps I see when doing rode tests for various reasons with the scanner on Ls installed vehicles ( oem trucks mostly and a few cars.)

Also, as has been stated before, a block test would be a good idea. A very small leak in a headgasket will eventually put enough "air" in the cooling system to cause them to overheat. It will usually result in much hotter temps than you are talking about, but I recall you saying you've never let it get over the 230 mark.

As for the compressor, I've seen many cases where a compressor was seizing or had internal problems that never resulted in a overheat condition. An with only a 4 rib belt if it has much of a problem it will snap it clean into. I've seen this on many occassions where there was no problem just an aged belt.

[dville_gt]

I haven't had to replace many of the thermostat's that are located in the lower hose area like the LS stuff. The few that I have done always seem to have a lower opening temp then the ones more commonly located in the upper hose areas. I assume that even though the thermostat has a lower rating the engine temps should normally be in the 210-220 range, as this is the normal temps I see when doing rode tests for various reasons with the scanner on Ls installed vehicles ( oem trucks mostly and a few cars.)

Also, as has been stated before, a block test would be a good idea. A very small leak in a headgasket will eventually put enough "air" in the cooling system to cause them to overheat. It will usually result in much hotter temps than you are talking about, but I recall you saying you've never let it get over the 230 mark.

As for the compressor, I've seen many cases where a compressor was seizing or had internal problems that never resulted in a overheat condition. An with only a 4 rib belt if it has much of a problem it will snap it clean into. I've seen this on many occassions where there was no problem just an aged belt.

What do you think about the idea that it could just be an incorrect radiator cap.

I let it cool last night, pulled the 1/8th plug I have in the sleeve in the upper radiator hose, there was some air in there. Filled it up, left the plug out all night. (Note: radiator cap was on the entire time, just the plug was out).

Came out this morning and the level had dropped down to level with the radiator filler neck and all of that coolant was now in the overflow tank.

Since the system was under no pressure and was cold it seems like the radiator cap should be sealing 100% and the level in the upper hose should have stayed consistent and not been able to go into the overflow.

The only problem with this theory is why the system is not over filling the overflow and puking all over the place when I am driving it normally.

It doesn't seem right though that when I add fluid into the upper that is higher than the filler it can just escape past the radiator cap into the overflow.

Any ideas? Going to get the part number for the correct cap and pick one up tonight.

[MstangsBware]

I can tell you from experiance that a bad cap will cause overheating issue for sure. I have ran into several cars while working on overheating problems where the only issue was the radaitor cap.

I would start at sqaure one like others have mentioned and get a block test. You could chase your tail for months if the problem is a blown HG.

[KBScobravert]

What do you think about the idea that it could just be an incorrect radiator cap.

I let it cool last night, pulled the 1/8th plug I have in the sleeve in the upper radiator hose, there was some air in there. Filled it up, left the plug out all night. (Note: radiator cap was on the entire time, just the plug was out).

Came out this morning and the level had dropped down to level with the radiator filler neck and all of that coolant was now in the overflow tank.

Since the system was under no pressure and was cold it seems like the radiator cap should be sealing 100% and the level in the upper hose should have stayed consistent and not been able to go into the overflow.

The only problem with this theory is why the system is not over filling the overflow and puking all over the place when I am driving it normally.

It doesn't seem right though that when I add fluid into the upper that is higher than the filler it can just escape past the radiator cap into the overflow.

Any ideas? Going to get the part number for the correct cap and pick one up tonight.

Since your radiator cap is lower than the upper hose I would put a non opening cap on the radiator and go the degas route. Take a look at how the 4v cooling systems are set up.

[shumpertdavid]

What do you think about the idea that it could just be an incorrect radiator cap.

I don't think the cap is going to be so much of a problem, you could always go the lever lock route if you think it is. I've had several customer cars that I could squeeze a hose with the engine cool and the cap on it and it would push coolant into the reservoir, yet under normal operating conditions it hold tight.

I've often wondered why it wouldn't try to push coolant out when it built some pressure but the system would operate fine.

[dville_gt]

Tried a new cap, no dice.

Anyone around Arlington have a combustion leak tester (obviously I'd need to buy the fluid)?

Car runs good, drives around at around the 186* thermostat for a few minutes. Then sits around 210 for a while, then slowly creeps up and up and up to about 230+ after 15-20 minutes of driving. It can actually maintain around 220-225* on the highway spinning about 3k rpm, but after that if you get off the highway it starts really wanting to get hot.

I pulled the plugs tonight and they all look great, none wet, steam cleaned, etc. Oil level looks great, no indication of any milkshake. I know this doesn't rule out a H/G, but if it's a h/g it must just be allowing cylinder pressure into the cooling system.

Strange side note, it seems like I can fill up that bleeder for ever and ever so slightly it will lose coolant. Fill it back up, looses a little coolant, fill it back up, looses a little coolant. Not talking about a lot here, but seems like it should eventually just be full. I am not sure if it still going into the over flow like it was yesterday although that is my only guess.

[dville_gt]

Also, how unlikely is it that the temp sensors (mounted in the cylinder head right by the exhaust header flange, could be affected by the heat from the uncoated headers. I know it is a long shot, but since the readings are coming from sensors that are so close I figured it might possibly be reading high due to the extreme heat right beside the sensor.

To give you an idea of what "close to the flange" means (the autometer sender is even worse as it is in the rear of then engine bay.

[greenbullitt]

not sure if others are closer, but i have one

[dville_gt]

not sure if others are closer, but i have one

Where are you at?

If it is too far I might just buy a kit, I know the kits are around $30 at Napa (at least that's what I paid a few years ago when I bought one). Guess I'll call tomorrow and figure out what they go for now. Probably not bad to have around for these instances.

Guess I'll have to pull both heads if it ends up being an H/G since the plugs all the plugs look good and there is no good indicators of a h/g thus no way to tell which head it is.