Head gasket time?

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Dec 20, 2011
So the cruiser started to run warm tHe other day after never previously getting above the half way mark on the temp gauge ever since a rework of the cooling system (new water pump, champion radiator, hoses, thermostat, etc).

I have not been loosing fluid and the last oil change had no evidence of any foreign substances according to my visual and the lab test.

When it does heat up it gets to about the 3/4 mark after running without issue for a good 20-30 minutes. It starts and runs fine with no white smoke or rough idle which to me seems like a pinhole somewhere that is bleeding off pressure. Pressure tested the cooling system and it slid from 15 to 10 psi within a half hour, but had an ill fitting cap so that test wasn't very conclusive.

Did a compression test yesterday

1. 130 psi
2. 130
3. 125
4. 100
5. 120
6. 125

So, is cyl #4 the culprit and is it the start of head gasket issues or is there something else worth testing or trying first?

Just got done taking out the radiator for a flush, took apart the thermostat housing and noticed a few things.

First off the fluid was pretty filthy, which I had seen from the top rad cap, but didn't know it was this bad throughout.

Second, there seemed to be a film over most pieces which I thought could be oil pointing to head gasket failure however, I took out a magnet and found that nearly all of this sludge stuck to the magnet immediately.

Third, there was a solid chunk of metalic sludge stuck over a small hole in the tstat. I have a new one on the way anyway.

Could this be engine debris cought in the cooling system from poor previous flushing to the point that it would reduce its capacity to cool, or, am I just trying to convince myself that it's not the head gasket that I have zero desire to change right now.
Flush the cooling system. A good way to do this is to mix up ~ gal of warm water with ` 1 CUP OF Cascade dishwashing powder.Mix it up till dissolved. Drain ~ a gallon of coolant from the system. Add the cascade mix to the system. Run the engine up to op temp. Shut down and leave it overnight. Start up the next morning, up to op temp. Shut down and let it cool until you can drain without steaming. (Would be nice if you could post pics of the garbage you will get out) Refill with demin water and flush(you can start the engine and let it run for ~ 15 mins to do this). Drain the water, then refill the system with coolant--(make sure to burp the system to get all the air out)
Lots of unknowns in your post. I would not be looking at the head gasket ust yet. Too many other things to address first. Your not losing coolant so you probably don't have a leak. Your thermostat is a good idea because if it doesn't fully open it is a restriction. Not sure what year you working on but if it has a clutch style fan check it for slop. If the clutch is slipping it is the same as not moving any air over the radiator resulting in higher temps. A blown head gasket will lose you some coolant and will definitely eventually over heat. If you pull your oil dipstick and it looks milky then you know for sure your head gasket is toast. If you have clear oil then look at the rest of the system. One way to eliminate combustion gases from the cooling system is to have a shop use a combustion gas leak detector on your cooling system. It basically "sniffs" your cooling system and passes the air from it though a fluid. If the fluid changes color then you have combustion gas in the system.
Thanks for the insight guys. I am going to continue to look at everything else, get the cooling system back together, clean it thoroughly and see if that solves this issue.

The oil looks good and I have had a head gasket go on another car so I'm familiar with the milkshake mess it leaves behind, but that was catching it very late in the game.

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