Coolant Leak, front engine

[DieselDobro]

After having two water pump changes and several other failed attempts to stop a front engine coolant leak I"ve come to my wits end.

It appears my engine is leaking coolant from at least two of the 10mm through bolts on either side of the water pump.

I can see coolant seeping from in between the timing cover and block just under where the through bolts are located. It leaks a little more while running than when static.

I have Mag particle inspected (Magnafluxed) the bolts and cadmium plated them. The integrity of the threads seems to be intact, no severe wear or corrosion. I have been using Permatex High Performance Thread sealant. (the stuff that smells like shoe polish). The last reassembly I let the sealant on the threads cure 72 hours before reintroducing coolant in the system. It started leaking right away.

No one I have talked, experienced with 6.5's or not, has heard of this problem.

The only thing I suspect now is the block threads possibly being cracked, but on both sides?

I have retapped the block threads beore reassembly as well. I haven't pulled the timing cover yet. But I'm about fresh out of ideas. Any help would be appreciated!!!

[More Power]

It's been a while, but I have heard of a corrosion problem that resulted in a coolant leak in the aluminum front cover.

Otherwise, I recommend using the Fel-Pro front cover gasket set. This set includes thin paper gasket where GM just used an anerobic sealant. I use a thin smear of silicone gasket sealer on both sides of the gasket. The long water pump bolts are cleaned, dried and then a thin smear of silicone sealant is applied to the bolt threads. I've not had a leak in this area.

Jim

[john8662]

MP's right, it's probably the front timing cover that's causing you grief.

Pull the harmonic balancer and remove other necessary components and remove the cover from the engine.

You'll likely find that the aluminum has been eaten away, like a worm has been in there. Seen a bunch of 6.2 front covers that have had this problem, don't know if it's a green vs. red antifreeze issue either, all 6.2's would have had the standard antifreeze.

J

[Robyn]

The front covers are installed at the factory with an anerobic sealant between the Cover and the block. The steel pump plate is mounted to the cover.
Either of these places can leak.

Drain the coolant and remove the accessories and the front cover.
You will have to remove the Harmonic balancer to do this but its no big deal.
remove the few very front pan bolts but dont mess with the other pan bolts lest you may cause a pan leak.

Clean the block and the cover well.
Use a gasket and some silicone (black) on the front cover and the water pump.
A little of the black silicone will do fine on the threads of the bolts.

Replace the front cover seal and use black RTV on the pan area when you bolt it back together.

Be sure to clean out the little groove in the front cover between the water passage and the timing cover part.

Once you do this your issues should resolve.
Be sure to look over the cover and the steel water pump back plate well for any errosion that may have eaten through.
I have never seen any of this, BUT, it could happen I suppose.


A note here, be sure your IP is marked and just unbolt the gear and the pump and let the pump hang on the High pressure lines.
The cover is doweled in two places so it will go right back to where it needs to be.
The IP on these has no marks so use a small scribe and a little straight edge and scribe the part line on the IP and the cover up top where the IP bolts up.

If you make a nice sharp line and set things back there you won't have to mess with TDC offset later.


You will need to pull the pump gear off but not the timing chain or sprockets.

One thing though, if the chain is loose replace it.

The cam sensor can be a bitch to get out so if its working fine leave it alone or at least wait to fight with it until the cover is off and on the bench.

Robyn

[DieselDobro]

Thanks to all, I appreciate the detailed responses. I'm about to go to surgery shortly.

I did the DSG Phazer gear mods over 6 years ago which happens to be the last time the timing cover was off.

I'll post what I find. Thanks, again.

Mark

[DieselDobro]

The timing cover looked good over all, (no noticable corrosion), on the gasket/ mating surfaces. The timimg cover gasket was just plain wore out.

I used a Fel-pro pump and plate set and Victor cover to block gasket (a left over). YZX seal and Permatex Ultra-Blue silicone on the reassembly. I used the Ultra blue on the water jacket bolts, too. Let it set overnight and added the coolant this morning before leaving for work.

All in all this seems to have stopped the coolant leak. I'll feel better with a couple of more days behind me.

This was the first R&R of the timing cover since installing the Phazer gears in December of 2000. I noticed the cam to pump gear had wore a nice gouge into the cover. The cam timing must have spaced the pump drive gear out a little farther than the original sprocket gear. The dual idler shafts also created quite noticable wear in the cover. Other than that the Phazer gears appeared to show no wear after 6+ years and 110,000 miles.

Thanks, Jim, John, and Robyn for the help.

[Robyn]

You are very welcome.
Always happy to help those in need.

I got a call from a fellow close to here that frequents the Place and he is rebuilding a 6.5
Drove over to his house and we did some serious looking at his truck and stuff.

Its way kewl to be able to meet some of the folks that we all meet here in the cyber garage.

Good luck

Robyn