Lift Pump to Injector Pump Mounting Leak - PeachParts Mercedes-Benz Forum

Shern · #1 05-18-2018, 02:35 PM

Boy am I spending some time on here lately... Three steps forward, two and a half steps backwards.

Couple weeks ago, rebuilt my lift pump and remounted it without incident.
Installed with new gasket and took special care removing the previous one.

Recently noticed a minor leak from what looks like each of the three studs. Difficult to tell up top but certainly on the bottom two. I've snugged each nut (with washer) down about as tight as I can.

I cannot be the first unlucky sap to have experienced this.
So frustrating...

What else can I do?

Album forum doesn't seem to like: https://imgur.com/a/vSYhCaW

ROLLGUY · #2 05-18-2018, 10:11 PM

If you cleaned it with a good degreaser, you could know for sure if it is leaking from there, or just residual. Some say it is not necessary to use any sealant, but I use Gasgacinch (basically rubber cement) on all these type of gaskets. I have yet to have a gasket leak after using this product. It also makes it easy to remove the gasket at a later time, as it does not dry hard.

Diesel911 · #3 05-18-2018, 10:41 PM

"Gasgacinch (basically rubber cement)" but takes a higher temp. I like that stuff. Hard to find out here.

The stuff absorbs into paper gasket material and if you coat and let dry you can apply several coats and sort of end up with a rubberized paper gasket.

ROLLGUY · #4 05-18-2018, 10:51 PM

It is also great for holding gaskets on while placing the part. I coat both the metal part and the gasket, and let it dry a bit. I actually used it today on a turbo drain tube. It is almost impossible to get the gasket to stay without it.

BillGrissom · #5 05-18-2018, 11:43 PM

A similar product I use is Permatex High Tack Gasket Sealant. It comes in a steel bottle w/ brush in cap. I think it is a butyl rubber and stays flexible. Cleans up w/ ethanol. Besides thin gaskets, I coat bolt threads with it which penetrate into water or oil cavities. Surely I used it on the lift pump I replaced a few years ago and no leaks. First-pass was worse. Since I didn't have the correct gasket and my son needed to take the car back far away, I used a round gasket I had. But the bolts were outside the gasket and the cantilevered load broke an ear off the lift pump. Had to switch to a backup pump and got the correct gasket that pass.

Shern · #6 05-19-2018, 02:43 AM

Bill, Rich, Diesel911, thank you. This is a great start.

Rich- Have degreased a few times, so can say rather confidently it's more than residual oil from the replacement. Also, that gascacinch must have been what you put on my valve cover gasket as that was the longest running dry gasket I've seen yet...

Diesel911- after your notes in the previous thread, I had a good long look at the posts, it's definitely coming from there rather than the gasket.

Bill- I'll see if I can get my hands on either compound. I did find your post in the archive and had been wondering what you did after you dealt with the broken "ere"

Question is, do you think I'll be able to reuse the paper gasket? It's only a couple weeks old, but admittedly I lack experience using paper gaskets and have no idea how they respond to installation/reinstallation.

I think bolstering the gasket and coating the threads should leave me in good shape.

What about something like loctite blue on the studs and nuts? Or should I go Gasgacinch or Permatex high tack sealant the whole way through?

BillGrissom · #7 05-19-2018, 02:37 PM

Loctite blue sounds smart. Can't recall if there are lock-washers w/ the nuts, but likely are. If the gasket is sound, should be re-usable, though cheap if you have time to wait. I never buy just 1 gasket. Can buy Permatex or Gasgacinch at any auto parts.

The lift pump w/ broken ear was trashed (can't weld back), but I had another one. Of course I didn't toss it because the innards may be needed some day. If you keep backup parts, maintenance is much easier. I have all parts from my failed engine.

Shern · #8 05-19-2018, 03:04 PM

Quote:

Originally Posted by BillGrissom

Loctite blue sounds smart. Can't recall if there are lock-washers w/ the nuts, but likely are. If the gasket is sound, should be re-usable, though cheap if you have time to wait. I never buy just 1 gasket. Can buy Permatex or Gasgacinch at any auto parts.

The lift pump w/ broken ear was trashed (can't weld back), but I had another one. Of course I didn't toss it because the innards may be needed some day. If you keep backup parts, maintenance is much easier. I have all parts from my failed engine.

Thanks for that Bill. In your experience, would loctite be necessary if I'm also using permatex/gasgacinch on the threads? Or does loctite do a better job?

Shern · #9 05-19-2018, 09:24 PM

Well, I've taken it off, cleaned it thoroughly and have given the gasket a good coating of permatex extra sticky. I gave the screw posts a little whacking and then coated them too, on the shaft and base. If it still weeps after this I think I'll have to live with it. Will report back in a few days.

Shern · #10 05-21-2018, 07:14 PM

Well, this did the job: Permatex high tack gasket sealant.

As always, thank you guys for the experience.