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Leaky timing cover

C

charm

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Everett, WA
I know this has been discussed before, several times. I've read those threads on several forums and I'm still having issues. And, of course, it's the bolt that's impossible to get to!

So, 360 in a D300, final stages of rebuilding the top end.

The bolt behind the lower radiator hose neck on the water pump was leaking. I tried a couple different things, retorque, new thread sealer, neither worked. I decided to remove everything, check to see if I had cleaned things well enough the first time, and reinstall. I could have cleaned things better the first time, the second time things are pristine. Threads in the block have had a tap run through them to clean them out, all traces of gasket and corrosion is gone from mating surfaces, bolts are torqued to 35 ft lbs per Chiltons guide. All of the bolts seem to be holding correctly except the same darn bolt, the one behind the lower radiator hose neck on the water pump. The one that requires pulling the water pump to deal with.

I've tried with and without thread sealer. This time I decided to try gasket maker. Still leaking.

I'm 99% certain it's from the bolt and not the hose. It appears like water is bubbling around the bolt but I suppose it's plausible that it could be coming from the hose and wicking around the head of the bolt, but it doesn't look like that's what's happening to me.

Any thoughts on how to plug the leak? Not looking forward to tearing the water pump off again, but I have accepted that as my fate.
 
Did you check the housing around that bolt for cracks. Dont know why it would be leaking coolant unless that bolt goes into the waterjacket in the block.
 
That bolt does go into the water jacket. Timing cover is new and appears to be in new condition (no cracks I can see).
 
Dont think I would remove the housing again then. Obviously the pump has to come off. Think I would find a water cure sealant and coat the whole bolt with a thin layer. Install the bolt far enough to engage the threads and pack is much extra sealant into the hole as can be. Tighten the bolt, install the pump, hoses and fill with coolant and let it sit a few hours before starting to allow everything cure before starting.
Short of that I am out of ideas.
Guess this explains the corrosion around the bolts even on factory installed housings.
I have always cleaned just the bolt. Coated them with high temp bearing grease and put them back in. Have never had a problem.
 
I was reading on some other forum that some folks add radiator stop leak when they do the timing cover. I am not a fan of radiator stop leak. But, what if I bought some and just dipped the bolt into it (with the water pump gasket maker)? Not enough material to do any damage, the material would be where I want it, it would be captive where I want it.

I'm also thinking I'll replace that bolt. While I cleaned and inspected it, if there's minor corrosion on the threads, I can envision that, maybe, might impact its ability to seal the water jacket.

Thoughts?
 
Update...

Fixed the leak (mostly). I used gasket maker and a new bolt. My best guess is that replacing the bolt did the most good. There were a couple slightly bent threads on it upon super close examination. They weren't bent enough to really grab while inserting the bolt, but, I'm guessing, bad enough to not seal and allow coolant through.

I said 'mostly' because it looks like the radiator needs a new core. It's just barely weeping. The top tank is down about an inch after a month of sitting, and not running until a few minutes ago...but that's for another thread.
 
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