Hummer gets hot and OIL light comes on

[Jeremy]

Alright, here's what's going on. Just looking for anybody who has had a similar situation and what the issue was.

My 07 Inline 5 H3 just recently started to heat up between halfway and three quarters when I come to a stop at a light or stop sign, etc. Then it will ding and the cluster says "OIL" and the red oil lamp comes on in the right corner of the cluster, under the speedometer. Then I start going again and it goes away and the temperature goes back down to halfway.

I checked the oil that was recently changed at a Valvoline and it was full and it wasn't black and it still isn't, I've been checking it every day. Then I found a leak on the top of my radiator. I patched it up with a soldering iron, put some JB Weld over that and let it dry. It still seeped out a little bit so I re-soldered it and then I put Quik Steel over that. It dried up and was hard as concrete. I drove it for a day and the Quik Steel was wet and mushy from the coolant. I scrapped it off and resoldered it AGAIN but didn't put anything over that. It leaked like a little bit one day and it doesn't seem to leak excessively anymore. It gets a little wet but I'm not losing coolant anymore. It still heats up though!!!

 

[adventr]

I'd definitely replace that radiator. It's probably not holding pressure...

Keeping the cooling system under pressure increases its efficiency.

 

[poncho1965]

X2. Sounds like it's getting way hot!

 

[4speedfunk]

Keep an eye on the oil. If it turns milky or looks like a Frappuccino...you got water in your crankcase. That usually points to a bad head gasket or a crack somewhere. This will thin the oil out and destroy a motor in very short order.

Definitely replace the radiator, as they are plastic, short-life components and designed to be "throw-away". The days of "tanking" and "re-coring" radiators are long gone. GM wants giraffe money for them, so most guys go aftermarket...$200 or so. Installation is easy and takes about an hour, so don't let some shop charge you $900 (like I've heard on the forums before). Its a good idea to throw a new thermostat and coolant in when you do the swap. Also, if you are over 90K miles, it would be a nice time to replace the water pump as well.

The concerning thing to me is the oil pressure light. Just because the motor gets hot...doesn't mean the oil pressure should drop low enough to trigger the light. You might replace the sending unit, as I have heard some reports that they are sometimes the cause. If you want to know for sure, you should install a mechanical oil pressure gauge and monitor it for a week or so. It should hold 20 psi at an idle, fully warmed up...although I have driven small blocks for years that only held 12 psi. Most lights come on at 10 psi or less, and if that is truly the case...then you most likely have an internal bearing issue. Whatever the cause...when oil light comes on, don't just stare at it and keep driving. Shut it off immediately until you know for sure the cause.

 

[Best4x4]

Also since it isn't cooling at a stop light and the temp rises replace your fan clutch. Cheap and simple thing to do, my wife's 07 was toast when I bought it. With the oil light I'd certainly check the oil, and honestly replace the oil pressure switch or inspect it (another thing I fixed on my wife's 07). Replace that radiator!!!! You can't ever seal a plastic tank radiator 100% with JB Weld (once it builds up pressure it'll just blow off or out the radiator tank).

 

[SedonaBound]

Overheating and oil light are separate issues.

Don't trust any band-aid fix on a plastic radiator; thermoplastic can't be practically repaired. Any patch is under pressure will eventually separate. All you can do is replace the radiator. You may have air in the system from the leaks but AFAIK, but there's no procedure for bleeding an H3 cooling system aside from running it with the rad cap off until it gets to normal temp.

The oil light maybe be from a bad sensor if you're lucky. How many miles on your engine? Do you know how well it was maintained before you bought it?

 

[Best4x4]

I've had good luck parking on a good incline with car ramps, and getting my 07 to burp out the air bubble. Replace the Radiator, fan clutch (check water pump pulley for play at this time), replace the oil pressure switch, and go from there.