Oil leak on top side

[corvairdog]

I've been battling a oil leak on the top side of my 66 Monza for a while now. I was told by Clarks to replace the oil filter filler gasket underneath which I did - http://www.corvair.com/user-cgi/search.cgi?part=C483A.

Then I was told to put more sealer on the bolt below where the oil continue to weep through. This didn't resolve it either. Anyone have any ideas? It's the 3rd time in the shop for this issue.

[bbodie52]

Did you carefully examine the mating surfaces on the engine and the oil filter adapter for damage or some foreign material that would prevent a good gasket seal? The only other place for oil to leak in this area is around or through the oil pressure warning light switch. If you clean and degrease the area, can you tell specifically where the oil is coming from?

With two clean and smooth mating surfaces, a fresh gasket, and all of the bolts properly torqued there isn't usually a problem with sealing this area. Is there a possibility of a hairline crack in the oil filter adapter that would permit oil to leak out?

[corvairdog]

Hi Brad,

The mechanic put a tracer in the oil and used a light and it's definitely coming from that bolt. I didn't install the gasket but I assume he cleaned and inspected the area. Not sure why you are mentioning the oil filter adapter no oil is leaking from that area.

Clark's recommendation is to put more sealer on that bolt which he is doing today for the 3rd time.

John

[boatbob2]

Are you SURE you have the correct bolt???Also you can add a plastic washer under the bolt head,

[bbodie52]

The oil filter adapter, shown below, is the entire casting that supports the generator/alternator, fan belt idler pulley, oil filter, fuel pump, and provides the oil filler and oil pressure warning switch.









Which bolt is the source of the leak?

[davemotohead]

Doug,,what bolt are you talking about?

[bbodie52]

It occurred to me that if oil is leaking around a bolt head, you could have a bolt installed in a hole that is too long for the depth of the threaded hole! Or, if you install a bolt that is not threaded all the way up to the bolt head, it could run out of threads before the bolt head comes into contact with the washer and aluminum casting, because there would be no more threads on the bolt shaft to screw into the bolt hole -- stopping the bolt from going in far enough. Look at the oil filter adapter on the left (for alternators). Notice the added height of the casting next to the alternator mounting area? These two mounting holes may require longer bolts. The other bolt holes near the fuel pump mount would require shorter bolts. If you install an incorrect bolt that is too long it may "bottom out" in a blind threaded hole. It may feel tight, and it may even look tight if you don't look closely. But if the bolt head does not contact the aluminum casting because the bolt is slightly too long or doesn't have enough threads and it bottoms out in the threaded hole, it may leave a slight air gap between the bolt head and the washer/aluminum casting -- enough for oil to leak out.

It is just a theory, but you should check to make sure that the bolt that is leaking oil is not too long.

[corvairdog]

Brad, this is an excellent theory. I appreciate all responses. It continues to leak. He applied the sealer to the bolt, let it set for 4 hours and then ran the car at idle for 20 minutes - no leak. I then drove the car for a good 20 minutes and it began leaking from that bolt. I'm going to see if Clark's can send me a new gasket and a bolt and have him try that.

Update - having Clark's send me a used oil filter housing in case that has a hairline crack in it.

[bbodie52]

Brad, this is an excellent theory. I appreciate all responses. It continues to leak. He applied the sealer to the bolt, let it set for 4 hours and then ran the car at idle for 20 minutes - no leak. I then drove the car for a good 20 minutes and it began leaking from that bolt. I'm going to see if Clark's can send me a new gasket and a bolt and have him try that.

I doubt you would need yet another gasket. The gasket would only be damaged and need replacing if you actually physically remove the oil filter/alternator adapter from the rear engine housing. It is usually damaged because it is a paper gasket and tends to stick in place and is damaged/separated and normally is not reusable when it is removed. Also, the gasket forms a seal between the adapter and the rear housing mating surfaces. It helps to seal any slight irregularities between the two machined mating surfaces, and helps to prevent oil from leaking out between the two metal surfaces. IT DOES NOT NECESSARILY CREATE A SEAL AROUND EACH BOLT! The bolt and washer tend to create their own seal when properly fitted and tightened. The bolts do not normally need any kind of chemical sealer, o-ring or gasket. They are installed "dry" or with a small amount of anti-seize compound brushed on the threads to protect the aluminum threads the steel bolt screws into. I have never had any difficulty getting the oil filter/alternator adapter and its associated bolts to seal and not leak. A fresh gasket installed on clean parts, and five 5/16-18 bolts with the threads coated with anti-seize compound and torqued to specs (7-13 ft. lbs.) is all that is needed.

I cannot find any specifications for the bolt lengths in the shop manual, parts catalog, assembly manual or on the Clark's Corvair Parts website. There are five bolts, and I think the two adjacent to the alternator would be one length, and the three bolts on the right, adjacent to the oil filler tube and fuel pump, would be shorter and all the same length. You never did say which bolt is leaking. But you should be able to simply remove it and compare its length with the similar bolts next to it to see if they are the same. My theory about one bolt being too long or not tightening down all the way is only a theory that would have to be confirmed through examination, but I can't imagine what else would permit oil to leak around the bolt. Let us know what you find.

[corvairdog]

The picture at the top of this thread clearly shows where the leak is coming from. I ordered a used housing, bolt set and gasket from Clark's to hopefully get this resolved. Car is going back in next Wednesday and I'll update the thread then. Thanks.

[bbodie52]

The picture at the top of this thread clearly shows where the leak is coming from...

The picture you refer to does not display on my PC. I had noticed earlier that some attempt had been made to embed a picture in your first posting, but it does not display. I tried to copy the associated URL that you embedded and to use it directly on the Web browser, but it comes back with ACCESS DENIED, so the website hosting the picture is probably not accessible because of embedded site security.

[Scott H]

The picture at the top of this thread clearly shows where the leak is coming from. I ordered a used housing, bolt set and gasket from Clark's to hopefully get this resolved. Car is going back in next Wednesday and I'll update the thread then. Thanks.

The site you have that picture hosted is password protected. You can see it but we cannot. Try to upload it here using the "Full Editor" - "Upload Attachment" feature so we can see it.

[corvairdog]

Here is the picture. Sorry for the confusion.

[bbodie52]

Well, it does look like an aftermarket bolt, which opens the possibility that it just might be too long and not fully seated against the top of the oil filter/alternator adapter. You indicated that you had ordered a new adapter, new bolts, and a new gasket from Clark's. It will be interesting to see if that corrects the problem with this "shotgun" approach -- to replace everything. You can compare the new bolts with the old and see if there is any significant difference.

I do like your oil cap, though!

[corvairdog]

I am going to have him compare the bolts before ripping it all out, in the off chance that the current one is too long. That would be a lot of $$$ spent on one bolt if that is the case! I'll post an update on Wednesday.

Regarding the oil cap, the car was owned by a long time Corvair enthusiast that was also a machinist. I guess he had access to a CNC machine and made all sorts of cool stuff for the car. He passed away in 2010 and I purchased the car from his wife in the fall. I've finished up the things he didn't like the seats (see my other posts) as well as updating the sound system and fixing odds and ends like the cruise control.