Antifreeze leak from water jacket side plate

[Mr. Close Reach]

Hello all,
My Moyer-rebuilt A4 with FWC has had a steadily increasing coolant leak over the last year or so. I thought the culprit was simply hose clamps (and that may have conitributed to the problem) but it's quite clear now that it is coming from the side plate.

Given that the engine did get a rebuild in the last 6 years or so (previous owner), is the gasket a likely cuplrit, or could there be another issue here? Just want to know before I start tearing things apart.

Thanks.

[hanleyclifford]

If you have the access you could remove the alternator and run the engine. This will give a good view of the side plate. By wiping with clean paper towels you should be able to spot the leak. Also to be considered: the inlet fitting and the two block drains. In addition check to see if the thermostat housing is the culprit.

[ILikeRust]

I don't see why it couldn't simply be the side plate gasket. Easy enough to check, although of course you have to drain the block first...

[ndutton]

If you remove the sideplate I recommend replacing the sideplate bolts with stainless studs installed with either JB Weld or red Loctite and fastening the plate down with external hex nuts and flat washers. No more threads to undo after years in the water jacket.

[Al Schober]

Take a look at the fasteners for the side plate. If they're hex head bolts, they are probably the leak and you should definately go to studs and nuts.

Al

[ndutton]

In my case I used stainless set screws, brass flat washers and brass hex nuts. If a dissimilar metals issue rears its ugly head, the softer hex nuts are sacrificial.

[ArtJ]

Be aware that once you remove the side plate the odds are that a couple
of the bolts will break off. Be prepared by having on hand the Moyer
stud replacements. Additionally, you must use a socket or some other
guide to avoid drilling thru the walls of the cylinders which are very close
to the side jacket.

Regards

Art

[ndutton]

I agree with Art that you'll likely break a bolt or two, they're really soft. The good news is . . . . they're really soft!

If the side of the block is still intact, a method I learned here to drill the stump dead center is to try and grind or file the broken end as flat as possible, replace the sideplate and use it as a drill guide to dimple the stump with a 5/16" drill bit. Once dimpled you can remove the plate and go at it with a smaller bit, working up to the proper diameter bit to retap the hole. It was the easiest drill-out and retap I've ever done.

[Mr. Close Reach]

studs and nuts

Finally got to the boat today and confirmed that the sideplate is secured with studs/nuts - I wonder if this "fix" was part of a typical Moyer rebuild or if a PO did the job?

Hopefully this saves me from drilling out/retapping anything - maybe I can just remove the plate, replace the gasket and replace the washers/nuts? There is definitely some leaking at the plate itself, but I also saw a few drops at one of the lower nuts (bottom right nut in the pic below). It might just flowing down to that point though.

Also, where is the block drain? Sounds like that will be the first step. My engine is in "backwards" with a v-drive so hopefully I'll be able to get to it.

[edwardc]

There are two block drains. One is behind the starter, and the other is behind the accessory drive. On the late-model blocks, the accessory drive one is positioned such that it can be extended straight out with a long 1/8" npt pipe nipple without hitting anything, and then capped. this allows for easy access.

On the early-model blocks, this can't be done, as the drain is located farther back on the block and totally behind the accessory drive body.

[thatch]

Mr Close,
As A4's go, yours, with it's nuts and studs, is in very good looking condition. I'm betting that a cleanup and proprely installed gasket will solve the leak problem. There are a couple of things worth mentioning at this point though, the first is concerning what pressure radiator cap you are using? Since we are dealing with temps under 200 degrees, a 4lb. cap is sufficient. Anything above that is just incouraging leaks. Secondly, I see some black alternator belt residue in the area that might indicate a belt alignment issue.
Tom

[Administrator]

Out of the question

As A4's go, yours, with it's nuts and studs, is in very good looking condition.

Before anyone suggests it, we are NOT moving from Butch's classic "Home of the Afourians" to "Home of the Nuts and Studs."

Bill

[Mr. Close Reach]

Mr Close,
As A4's go, yours, with it's nuts and studs, is in very good looking condition. I'm betting that a cleanup and proprely installed gasket will solve the leak problem. There are a couple of things worth mentioning at this point though, the first is concerning what pressure radiator cap you are using? Since we are dealing with temps under 200 degrees, a 4lb. cap is sufficient. Anything above that is just incouraging leaks. Secondly, I see some black alternator belt residue in the area that might indicate a belt alignment issue.
Tom

If it was a Moyer FW kit, wouldn't the correct cap be on there?
RE: the residue, yes that was from running with a loose belt for half a season...fixed now.

[hanleyclifford]

Before anyone suggests it, we are NOT moving from Butch's classic "Home of the Afourians" to "Home of the Nuts and Studs."

Bill

But maybe we could have a little section under "wish list"?