I just came back from the mechanic, to try and find out what was causing my high temp readings and here is what took place. He tested my thermostat and it was OK. Second maybe there is a blocked passage in the radiator, like opensourceguy stated B4, and third which is the worst is that there could be a small leak in my intake manifold some where.

Maybe a seal or gasket or something, right now I am so HEATED .(No pun intended) that I'm sure it'* somewhere in that vacinity. My mechanic is an excellent one, and I can trust him, but DAMN! I just took it out with plenty of major work done and NOW THIS .

If this is the problem, I will also change my sensors as well. He also suggested the in-expensive alternatives, Use a good Rad flush, or if that doesn't do it and there is no other problems, replace the rad!!!!!

Someone please chime in and kick a vesre or two with more input!

Thanks Guys, One!

do the flush thing and while your at it run a hose in the top of the rad and check if the water flows easiliy out the bottom hose connection without backing up the top.

Thanks, I will try that option, also I took my bonnie a while back to one of those 15 minute oil change locations and I had a power flush done. It did remove a lot of bull****, but also about a week later I experienced losing pressure and the car would run hot and stall. Found out that the power flush had caused several large pin holes in the rad. Had it repaired and since then I've always had this overheating problem.

If you have to replace it, it won't be that bad; I replaced mine a while back and it wasn't as hard as I thought it would be. Good luck with it.

It'* not hard at all, and you should be able to get the radiator for no more then $150 (shop around). But I agree, one more flush before hand wouldn't hurt. Some people fear doing a power flush for the very reason you stated: Finding a problem afterwards. But it'* just like a tranny fluid change on a high mileage car that'* never had it done before: Sure, you run the risk of it messing up, but that'* only if it had a problem to begin with, and was going to happen soon, anyways.

if you do replace the rad, keep in mind that there are differences between the 1988-1991 SSE years. '91 has a thicker rad vs. '90. Keep a lookout for any potential incompatabilities.

If you need a radiator, I have one that is only about a year old.
I'd sell it for cheap!
I'm parting out a 90 Bonne that I bought on Ebay with a bad motor. Don't have the time to fix it.

EDIT: ahhh, my first post. Although I've been a guest for a month or so now, just started posting.

Nice to see you here RareGMFan! I knew you posted here, but haven't really seen you post other than this thread.
Greetings to all!

Oh wait, you have an SSE.....This is out of an LE. Likely won't work?

SSE has an oil cooler integrated into the rad, so no, it has to be an SSE unit. :(

Wouldn't it also need the plug for the "Low Coolant" indicator/sensor for the DIC, which the LE radiator doesn't have?

-What'* up, Dave? Man....a-body forums, w-body forums, and now the bonneville club......you get around. J/K. Yeah, I posted a bit initially when I joined, but haven't had much time since (not even on the other car forums).