Thread: 03 Top Swap running hot UP AND RUNNING

For the past couple of weeks my brothers 03 top swap has been running hot. The temp gauge would get to the 210 mark and not go any lower than about 200. His aeroforce was also reading at around 200. The fans do turn on but the temperature does not drop to normal. Same thing when driving on the highway on his way to work. The temperature would stay around 200 and not drop (about a 30 mile commute). He did have to add coolant every few days as coolant was leaking internally somewhere. The car had been running fine after the top swap.

Here are some things that have been done:

Bled the system and there was no air in the system
Replaced the 180 T-stat with a 195
Replaced the waterpump
Replaced the radiator cap
Replaced the duralast ECT sensor with a delco
Removed the LIM and double checked the aluminum LIM gaskets (they were ok). During this time we did notice that the oil was milky on the oil cap.

We didn't go any lower into the heads to make sure the gaskets are ok or if the heads are ok.

Even after all of these changes the car is still running hot.

I'm looking for more ideas to figure this thing out.

If the oil is milky you might have a bad head or gasket.

Originally Posted by QUICKSILVER462

200 is not hot, 200 is not even boiling. 210 is not hot either. As long as coolant and pressure are maintained, 230 is starting to get hot. If there is a large inconsistancy in the temperature during operation, I would say there is a problem.

Although that is true. The car should drop in temperature when driving on a long stretch of highway with the cooler air coming in. The temperature should be about the same as my 99.

If the oil is milky you might have a bad head or gasket.

I'm starting to lean to either one of these as being the problem.

Did you use felpro head gaskets?

Originally Posted by BlackGT97

Did you use felpro head gaskets?

Yeah we did. I have his car this week since my commute to work is short and it's still eating coolant. It will be coming apart again to inspect the gaskets and the heads.

i would think his top swap would make a bit more heat then your gt

Originally Posted by Seachicken

i would think his top swap would make a bit more heat then your gt

Yer makin' that up.

Originally Posted by SlowNA06

Yer makin' that up.

I'm confused by the contradiction of your statements.

The car is running hot at 200 while driving on the highway. I put in a 195F thermostat.
195F will open around 195F to an engine, that's very close to 200F. Running at 210F isn't very hot if you have stock fan settings.

The oil is milky, it is leaking coolant internally. We don't know what the issue is.
If you are using coolant internally, you have a serious problem that needs to be addressed ASAP. That is ..if your milky oil wasn't caused by a little coolant in the oil from doing the heads. Keep in mind the steel oil pan on most of these motors will hold 3/8" of lfuid below the drain plug. How much coolant is it going through? Is the engine burning coolant, you can tell by the exhaust.

Tell us more about the top swap. Parts you used for gaskets, if you sprayed the HG's with copper spray, if you used ARP bolts or stockers, or reused.

Originally Posted by BillBoost37

I'm confused by the contradiction of your statements.

The car is running hot at 200 while driving on the highway. I put in a 195F thermostat.
195F will open around 195F to an engine, that's very close to 200F. Running at 210F isn't very hot if you have stock fan settings.

The car was even running hot with the 180 t-stat. The fan settings are set to 185. It just sits at around 210 all day regardless. If I remember correctly my brother did say that there were a couple times that it did exceed that temperature.

The oil is milky, it is leaking coolant internally. We don't know what the issue is.
If you are using coolant internally, you have a serious problem that needs to be addressed ASAP. That is ..if your milky oil wasn't caused by a little coolant in the oil from doing the heads. Keep in mind the steel oil pan on most of these motors will hold 3/8" of lfuid below the drain plug. How much coolant is it going through? Is the engine burning coolant, you can tell by the exhaust.

It is possible that a little coolant got in. Anything is possible. But when we did the swap we changed the oil and put clean new oil in after a few hundred miles. When we took some of it apart last weekend there was milky oil on the oil cap. I didn't take the valve covers off. But everything was cleaned prior to installing parts. I can't really tell from the exhaust but I will double check. Regardless it's coming apart starting this weekend for inspection.

Tell us more about the top swap. Parts you used for gaskets, if you sprayed the HG's with copper spray, if you used ARP bolts or stockers, or reused.

The LIM gaskets were GM aluminum and the head gaskets were felpro. As far as bolts they are stockers and I am not sure if my bro sprayed copper spray on them. He had the heads on by the time I got home but for now until I ask him I'm going to say no that it was not used.

New stock bolts or did you reuse them?

A little update. Finally pulled off the heads and found this on the front one. The gasket appears to have failed on the center and on the left as well. The rear gasket was fine. The heads themselves look ok but we will be getting a second opinion from a shop. There was definitely coolant and oil mixing in the LIM and the heads. Also removed some of the carbon build up from the center.

Just got word from the machinist at the shop. One head was cracked and the other was fine. I forgot to mark the bad one to see if that was the issue. He is going to see if he can fix it. If not then a replacement would be needed.

If it cracked between the valves like 90% of all 3800 heads, then just bolt it down and run it.

Originally Posted by Fivefingerdeathpunch

If it cracked between the valves like 90% of all 3800 heads, then just bolt it down and run it.

I don't know GM'a 3.8 sc motors but I know my head on my super coupe thunderbird was like this and I lost compression because of it..

They are in the process of fixing the bad one. Should have it by monday.