Hi All,

Hoping someone has a suggestion. A couple months back I replaced timing chain, gears and water pump. When I put the new pump on the front cover the lower left 1/4" bolt was not grabbing. I was able to close up the hole and get the bolt to tighten. I put a couple hundred miles on the car this summer and noticed yesterday when I got home a little antifreeze on the floor. Yep that same bolt came loose. Seems to only leak a little when the rpm's are up.

Has anyone been able to successfully put a slightly larger bolt or different thread bolt in place that would tighten? I really don't want to take the cover off again

Thanks, Joe

 

I don't know if this is the right way to do it but...I had the same problem and I took the front cover off, flattened the burr around the screw hole a bit, then reinstalled it and used some Right Stuff" around the screw, screwed it in being careful not to over tighten it and it's held for three years.
Perhaps someone has a better, more professional solution, but it worked for me.

 

I think the only sure way is to remove the cover and either replace it or weld a nut on the backside. I've read about people running a tap with a larger sized thread through it. But the concern there is the chance of putting metal shavings inside the engine. I wonder if you could get a metric self-tapping bolt that's slightly larger? There still may be a risk of pushing metal into the engine but that may be a call you need to make. John

 

No reason why you shouldn't be able to tap it out a little bigger and use a larger screw, but there may be a bit of drilling involved, and you'd need to remove a bunch of stuff to get clearance for the drill.
Your best bet would be to use the next size up metric fastener, as this will represent a "half-step" up in size and require less drilling (it will also create a humorous situation when the next owner invents some new words for you when he has to change the water pump).

A 1/4x20 screw requires a 13/64" hole to be drilled, which is about 5.16mm, and if it's stripped out is probably closer to ¼" in diameter, which is about 6.35mm.

An M7 screw requires a 6.0mm hole and has a pitch diameter of 6.3mm, so could probably be tapped without even drilling, and would hold well enough if you didn't overtorque it.

An M8 screw requires a 6.8mm hole, while a 5/16x24 requires 9/32", which is about 7.14mm, so even if you had to go to M8, the hole would be smaller than a 5/16x24.

If you can't tap it without drilling, or get a drill in there the right way, then you'll have to take it off and do the job right, with a 5/16" screw.

... And I wouldn't worry too much about a few metal shavings getting into the water jacket - you should see the crap that ends up in there after 40 years anyway.

- Eric

edit: just re-read and thought about it again - that screw goes through a hole in the water pump and into the timing chain area, not into the water jacket.
Getting some shavings in there would be distasteful, but, at worst, those that got past the magnetic drain plug would run through the oil pump once and be trapped by the oil filter. They're very soft steel, so the oil pump would survive.

If you were able to tap for a 7mm without drilling, and used grease on the tap, you could probably do it with no shavings getting into the engine.

 

Eric, I'd have to run out to the garage and look to be sure. But don't all the bolt holes also go into the timing chain area?

John

 

Yes, John - I think you were writing at the same time I was.

- Eric

 

The 1/4-20 bolts on the bottom of the pump go into the timing chain cavity. The two on the top are outside the block. The four larger bolts thread into the block in blind holes.

One possible fix is to try the epoxy thread repair material sold by Locktite. This stuff is not very strong but it might be good enough for this application. I'd take care to swab the threads in the hole with lacquer thinner to remove all oil, then use the epoxy with the bolt. Let it harden then try to tighten the bolt as much as possible without breaking the epoxy. Alternately, you MIGHT be able to install a 1/4-20 Helicoil in the cover. Use grease on the drill bit and tap to catch any chips, and be very careful removing the drive tang from the installed Helicoil. Of course, once you remove the accessories and pump to do this, you're only a harmonic balancer away from getting the front cover off and fixing it the right way...

 

Thanks everyone for the quick replies. I pulled the bolt out and the metal from the cover was wrapped around it still. I guess it just gave out. I think I am going to try a 7mm bolt. If it doesn't work I guess the cover is coming back off. Well, at least everything is clean.

 

For whatever it's worth, 7mm is a bit of an oddball size.
They are out there (as are the taps), but may not be in the first place you look.

- Eric

 

Thanks Eric, yeah it be too easy otherwise

 

Well I was able to sneak a 7mm tap into a 6mm 12pt socket on a 3 inch extension with a 1/4 inch ratchet in b/t the fan and water pump pulley without removing anything. It took a little effort but I was able to run the tap into the cover. Used plenty of grease on the tap then cleaned up best I could. Added a little sealer on the new 7Mm bolt and it tightened right up. Didn't have a chance to test drive yet. Hoping it works, if so it cost me a total of 80 cents

 

Well if its coming off, just replace it. Timing covers are a dime a dozen and I'm sure you could probably get someone to ship you a good one for $20 or less.

John

 

Test drove tonight, all is good, no more leak. Thanks everyone for your help.

Joe

 

Good ol' American ingenuity'll take care of it every time.

Glad you got it fixed!

Gonna be at Englishtown in the rain tomorrow?

- Eric

 

Thanks Eric, no Englishtown for me, just work

 

Me neither, as it turns out - too wet. Tomorrow's looking good, though!

 

MD -- couldnt you just use a 1/4 self-tapping screw in it? The threads are a bit larger than a 1/4-20 bolt - eh? I had it happen once - only i was lucky - it happened to me on a top exposed bolt!!

 

Never enough time to do it right the first time, but always enough the second time around

 

Maybe, but he said that the old threads came out on the end of the bolt, so there would be VERY little material for the new screw to cut.

He's now got a new screw threaded into the hole, which, after it was stripped, was the correct tap drill diameter for the new screw he threaded into it.

- Eric