Thermostat bolts / threads?

The two bolts in my thermostat that have apparently been loose the whole time since I got my car I was thinking the water pump was leaking through a hole thing but I noticed that I either have the wrong bolts or threads ruined from over tightening.

The two bolts I have fit but slip once you start getting any amount of torque on them. They have the numbers 10.9 on them. Does anyone have pictures of the correct bolts for the thermostat housing? It's a 2005 and it has a aluminum housing.

I might need a thread repair kit but want to make sure my bolts are correct first.

The bolt heads on mine are corroded, so I'm not able to see what's stamped on them. However, I can't imagine anyone replacing the factory bolts with ones that are smaller. Are you certain that the o-ring is completely compressed?

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Originally Posted by avguy

The bolt heads on mine are corroded, so I'm not able to see what's stamped on them. However, I can't imagine anyone replacing the factory bolts with ones that are smaller. Are you certain that the o-ring is completely compressed?

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I tested out what you said today by removing the housing again and putting the bolts in with nothing and they did go in further than with it on. I believe they are correct I see 10.9 bolts elsewhere on the engine but no matter what im not able to attach this thermostat housing so I've ordered new gaskets.

But do you think it's a possibility that my housing could be cheap and need to be modified by changing the the thickness of it a little? It's a metal one that was already on it when I bought it.

Sorry but your information is sketchy and I'm not really understanding exactly what's going on. You acquired this Aveo some (unknown) time ago, and it sounds like you identified a leak at the t-stat housing. I will tell you that a PO installed the metal housing, because all '05 Aveos came from the factory with a plastic housing. So if those bolts had been installed loose back then, then I can't imagine how it wouldn't have been overheating regularly from the time the t-stat replacement was done, because it would never have been able to hold the proper coolant level.

And I'm also not clear on the part about threading the bolts in further with the housing removed. Beside threading the bolts in further, did you try to see if they would hold torque using spacers similar to the housing depth? If not, you need to make sure the threads are not stripped. But perhaps you've already done that and just didn't mention it.

The answer to your question is that it's highly unlikely the metal t-stat housing needs to be modified, because these parts basically all come from one or two factories and have little variation. Bottom line is that I'm not at all clear exactly what the problem is, so it would be helpful if you added more detail and filled in some of the blanks.

Solved the issue. I don't agree that anything I said was sketchy and I take that as an insult.

The radiator wasn't bolted down and caused the Tstat threads to strip, the gaskets were indeed compressed. Got a couple of them from rockauto for 6 bucks and had no success.

I did a temporary fix via https://www.youtube.com/watch?v=soOvDuwfnQA that video and some soft 14gauge stranded copper coated zinc wire I had laying around in bulk from ebay. Eventually I might do helicoil or a bigger threads with custom bolts at some point.