My low coolant light has been coming on repeatedly after topping off a few times and I noticed some standing coolant that appears to be coming from the thermostat housing. I just disconnected the housing to see if there was anything obvious I could deal with. When I put the t-stat back in I noticed that I could rock it back and forth a bit. Should it be totally snug or does that get tightened when you put the top of the housing back on. Just wondering if it was loose to begin with or if that was caused by me taking it out to look at it. Also, do you put some type of additional sealant on it?

Also, regarding the optispark...some coolant spilled down in that area when I did the above and I was wondering if those things get fried just from that type of contact or does the engine have to be running at the time for it to be problem.

Thanks for any help and sorry about the lack correct terminology.

 

The thermostat does not require sealant since there is a gasket built into it. It should just sit in place, then the water neck bolts on top. Don't overtighten the bolts or it can help it to leak worse. If it still leaks check to make sure the gasket isn't ripped or messed up.

Optis are a crapshoot, but for that reasonably small amount of coolant I would not worry about it.

 

Thanks. Does the thermostat fit snug or should I be able to rock it back and forth like I mentioned? It has a little play it in when I move it from side to side.

 

The LT1 t'stat has a rubber ring around the outside edge, which should fit flat in the recess in the housing, and should not "rock".

Courtesy of Shoebox:

http://shbox.com/1/tstat.jpg

 

If the diameter of the o-ring is a little smaller than the opening in the pump, that is ok. There might be a tiny bit of slack.

 

I guess "rock" was not the best word to use. Yes, it does have some "slack". I thought maybe that was the problem but evidently not. I guess I'll have to get a new o-ring if that's something I can get separately. The o-ring looks good to my untrained eye but somethings causing that coolant to seep out. I'm also a little confused because when I look up the parts for a 94Z28 they show a gasket that looks like it would fit where the water neck connects as well showing the o-ring.

 

Does the t'stat you are installing have a thick rubber ring around the edge that gets sandwiched between the housing and the neck, like the one shown in the link? Is it the correct type for an LT1?

 

Yes, it's the right one. It does have the o-ring. The ring isn't really that thick to me but it is the right one. It appears to fit properly around the thermostat.

 

Use Vaseline on the o-ring for a good seal. That should fix the leak,unless the o-ring has a nick in it.

 

If the coolant is seeping out of the thermostat housing where it connects to the water neck is the thermostat/o-ring and/or surface of the housing or waterneck the only possible culprit or is there anything else that comes into play. For example if their is still air in the system would that also be a possible source of the problem?