425 front cover gasket blown

[Richard001]

Before you reassemble the water pump manifold, after removing any gasket material, check to see if the mating surfaces are flat.

The simplest way to do this is to take a flat steel or Al plate, tape a piece of sandpaper on it and rub the manifold over it a few times. If the surfaces are flat, the entire mating surface will show some marks from the sandpaper. If not, then more rubbing will correct the surface and make it flat and true.

Now looking at the manifold photo, there maybe a problem with the pump gear and prevent you from doing what I just described. The next best thing I can think of is using a straightedge and a feeler gage. If the pump manifold surfaces are more that a few thousands of an inch from being flat and true, you need to fix it.

Richard

 

[weathda]

I'll put a straight edge and feeler gauge on it to check it. Thanks.

Also, how does the governor drive gear come off the case? The service manual doesn't really describe the removal - that I can find. All I see is a thrust washer behind the gear. Does it just press on and pull off? It seems like it's in good condition, but I ordered a new one.

 

[weathda]

Figured I'd post an update. What I thought would be a straight forward job has turned into a bit of winter project. I started not to post this, but maybe you can learn from my mistakes.

Got the new governor gear installed, new internal oil orings, new crank seal, installed cover,pump, and put back together. Had no issues. Almost home free.

Mistake #1. In my haste, I didn't clean the three skinny 6mm water pump bolts which were going in a bit tight. Looked like they had a bit of corrosion on them. The last one I was tightening down snapped off in the block.

I could not fathom tearing this thing back apart just because that little stud broke. Should've stepped away and let everything sink in.

Mistake #2. In a haze, in my panic and figuring rather than pull everything off that I had just installed, I ran a left handed drill bit in to try and drill the stud out. Should've just removed everything and could probably have extracted the bolt with some vice grips or an easy out. Anyway, the drill got off into the aluminum block and cover which is super soft. I ended up tearing the gasket, eating into the side of the block. I made everything worse and still had to take everything off.

Anyway, I surveyed my drilled holes. Tapped the holes I'd drilled and inserted studs with locktite sealant and then cut the studs off. Kinda like block stitching. Drilled the stud bolt hole.

Mistake #3 Started tapping the hole for the pump bolt with a 1/4" tap and the tap broke off in the block. I think it was digging into part of the old 6mm bolt stud. The long skinny tap flexed just enough that it snapped. Sick again.

I go to the auto parts store and buy some high temp JB Weld. Packed all the crevises and stud passage with weld. Sanded flush to just create flat sealing surface.

Luckily the 620D has a two threaded holes on top of the block just above this water pump bolt that broke. I figured maybe I could make a bracket that will allow me to tighten down the cover.

Order gasket kit #2. New seals, orings, and crank seal going in again.

On the upside, I did fix the broken dip stick tube bracket.

 

[Richard001]

I guess it's the old "live and learn" technique.

Next time you have an issue with getting bolts out, use some penetrating oil. When putting bolts back in, especially steel into aluminum, use some anti-size.

Lets hope your solution works.

 

[weathda]

Definitely a live and learn ordeal, Richard. This time I took the time to clean the bolts up good. Good advice.

I'm feeling pretty good about it. I'm giving it plenty of time to set and cure before I button it up, add liquids and give her a go.

 

[Richard001]

Just had a thought, the bolt that goes against the pump housing should have a lock nut otherwise it will work loose. If there is no room for a lock nut, then use a thread locker and flow the directions on the bottle.

Richard

 

[weathda]

I put red loctite on both nuts. Do you think it would still work loose?

 

[Richard001]

I put red loctite on both nuts. Do you think it would still work loose?

If you cleaned the threads on both the bolt and the nut, it should be OK.

Richard