Yet another coolant leak (Page 3/5) Cliff Pennock NOV 06, 12:44 PM Come to think of it, the cap I got from rockauto not too long ago and it's the only one they've got, so getting a new one isn't going to do any good. theogre NOV 06, 02:18 PM quote Originally posted by Cliff Pennock: It might very well be the cap. I had replaced it some time ago and one thing I immediately noticed about this cap was that it hardly took any effort to close it. My old cap took considerable effort to close. Take T-stat cap off. Look @ bottom Does rubber fill the whole metal shell. If true was MotoRad Cap maybe w/ another brand name & doesn't fit right or not @ all depending on T-stat house. See https://www.fiero.nl/forum/Forum2/HTML/146523.html Cliff Pennock NOV 06, 04:23 PM I removed the cap and thermostat just so I could make a comparison. Just to clarify: The "new" cap takes no effort whatsoever to close, while the "original" cap apparently takes more elbow grease than I can supply without modding something. Here are the two caps I have. The one on the right is the "new" cap and it leaks a lot of coolant. I bought it recently from RockAuto. The one on the left is the cap that was on it when I bought the car (27 years ago) and which I, for some reason, can't get to close anymore. You can clearly see that the "original" has the rubber go all the way to the edge while the new one has a smaller rubber seal. The new cap is also considerably higher than the original cap: You can see there is much more space between the rubber seal and the locking lips on the new cap than on the original cap (although it's a bit exaggerated by the smaller diameter of the seal, but the differense is still considerable): You can also clearly see why it hardly takes any effort to close the new cap: Cliff Pennock NOV 06, 04:24 PM As for the thermostats, the one on the right is the one I have in the car now. I suspect it is stuck open - it certainly looks different than the other two: (Yes, I know the sealing ring of the one in the middle is kaput) sleek fiero NOV 06, 04:58 PM Hi Cliff; Have you tried your caps on with the t-stat removed. The caps normally are quite tight to install. I use my water pump pliers to remove and install mine. I got mine at Rock auto and they had several different brands and prices. The really cheap stuff is from China. I think I got Gates or AC Delco and it seals fine and the rubber gasket should go all the way to the outside. sleek sleek fiero NOV 06, 07:45 PM Hi Cliff; As the ogre says Stant is gone but there are options . I went to the Gates site and this cap is available part # 31313. Any parts store that deals with gates should be able to get this for you. Hope this helps. sleek sleek fiero NOV 06, 07:58 PM They are still available from ACDelco Part # 12R16. The original GM part number is 19114590. They Used the same caps on other vehicle such as chev citation. It is the same cap for all model Year whether 2.5 or 2.8. sleek Patrick NOV 06, 08:17 PM With the newer style thermostat housing caps (the ones where the cap is able to rotate independently of the rubber seal), pliers of any sort should not be required to loosen or tighten the cap. (Using pliers can possibly deform the cap and/or the top of the housing.) I just use a wet rag to help get a good grip. sleek fiero NOV 06, 08:58 PM hey Patrick when we get older and arthritic it is way easier to use pliers. And the cap I have is the new design from gates. My point is that it's unlikely that the thermostat stem would stop the cap from going into the lock position. sleek Patrick NOV 06, 10:02 PM quote Originally posted by sleek fiero: hey Patrick when we get older and arthritic it is way easier to use pliers. Bill, I'll be 68 next month... but I refuse to get "older".