Anyone have issues with thermostat housing bolts backing out? I've got a 79 berlinetta with a 350 sbc (not sure of the year). The previous owner installed an Edelbrock Performer aluminum intake and about once a month a small leak develops in the thermostat housing. The bolts are loose and after re-torque to 20 ft lbs the leak goes away, for about a month. I've removed/reinstalled the housing with a fresh gasket, thread sealer on the bolts and they still wiggle loose. My last effort was to put a little blue loctite but I'm not confident that will do the trick. Anything else I should try before declaring the manifold bad and getting a new one?

 

Well I'd wait and see if the blue locktite works,sounds like the threads are getting worn out on the intake,maybe run a thread chaser in it and use new bolts with blue locktite..
Another option might be use red locktite with studs and locknuts instead of bolts to save the manifold.

 

Agree 100%

Thread sealer and locktite have two different job. All the sealer does is take up space because the bolt the intake will grow and shrink at different rates as the car warms up and cools down. It is not suppose to get hard or even grab the metal. Its very easy to clean off. I do not think the intake is drilled through to anything so there is no reason for thread sealer. Locktite(s) will get hard and bond to the metals the red is stronger. As long as you cleaned the threads there is a very good chance your done till you need a new thermostat. Assuming you used a new gasket this time.

How loose do the bolts feel side to side before they are tight? If it is sloppy you may need a helicoil install. "For me" I would skip the red lock tight and go right to helicoil repair but for me its a pretty simple repair, I have a drawer full of them and all the tools to install them. This is one of those repairs that once it is done you should never have to mess with it again its better then new. You would be going from very soft aluminum thread to a hardened stainless steel one. If you or a buddy have never done this type of repair just try the red loctite first.

 

Thanks for all the replies. I'm nervous about chasing the threads as the bolt holes go through the manifold, i.e. there is radiator fluid in the bolt holes when I remove them. I'm concerned about getting bits of aluminum in the fluid/intake from trying to clean up the threads. I've never done helicoil before, sounds like it might be worth the learning if the blue loctite doesn't work.

I've got a new issue now where the driver door doesn't always latch closed... I have to fiddle with the latch for 10 minutes and then all the sudden it starts working again. Scary drive home as I'm afraid the door will swing open as I'm rounding a corner. But that's a next weekend issue...

 

Second gens are notorious for sagging door this starts with the hinge bushing.. This means the striker and latch must align the door during the closing process. They where not designed for that. If you open your door can you lift from the back of the door to check the hinge for play. Also if you look at the striker how does it look? Is the latch bolts tight? To fix this first you repair the door hinge (they may need replaced). Then get the door adjusted. If you still have an issue I would replace the striker. Last thing to replace is the latch itself.

If the door is not sagging you could try some spray grease on the latch and re-adjust the door. (see youtube for how to adjust doors)

If someone "restored" this car they may have done some of the work for you. So maybe they fixed the hinges got it work decent and now the latch is a problem mostly because when the door was sagging it took some serious wear. Getting the door re adjusted can be a pain. If its your first time plan on it taking awhile. The hinges are very adjustable which means you can get in any car that was not wrecked but it also means getting it dead on is an art form.

How common was this issue? I bought my 1974 Z in 1979 with 56,000 miles on it. The doors sagged. I got to it about a year after I bought it because of the issue you described. I had to replace the hinge and the striker on the drivers side and oddly one of the bolts to the latch had fallen out. The passenger side just need bushings. Then in 82 I bough a 72. It needed bushings only in both side. I did those right away. The drivers hinge was just on the edge of needed replace but this car was my daily so I just dropped the bushing in. I only paid $200 for the car and good used hinges did not last long at the yard. If you put the new bushing in the hinge and it just falls in or the hole is out of round the hinge is shot. FYI all second gens are the same. GM never addressed the issue to the best of my knowledge. Back then those cars only had a 12 month warranty so they did not care.

There are a lot of other How too videos on this subject and even more on general door adjustment. I have done the process on a half a dozen cars I still like to watch videos to freshen myself up on something I did 20-30 years ago.

 

Awesome! Thanks for the tips! I'll post some pics this weekend as I start to wrestle with it. The last door I adjusted was on a '77 Ram Charger back in the 90's. It's been a few years.

 

Well, hinges seemed good. Doors don't drop upon opening and I can't wiggle them at all from the rear of the door. Striker and latch look like they have been abused in the past, but doing a sloooow close on the door they don't feel like they are binding at the moment. I snugged everything up and lubricated the latch. Made a tiny adjustment on the striker as it looks like the door wants to close in a little more. But so far seems to be opening and closing without issues. I'll replace the window felts probably in January (Christmas is hitting the wallet pretty hard) and take a good look at the latching mechanism then to see if it needs replacing.

Thanks again for everyone's tips!