Bad luck with primer pumps? - PeachParts Mercedes-Benz Forum

slm4996 · #1 12-21-2007, 05:21 PM

Hello averyone, this is my first post to the forum even tho I have been lurking for almost a year now.
Anyway I have just replaced the primer pump on my 1980 300SD.

Twice,
soon to be three times.

I replaced an old style white knob with one of the new bosch models and the thing started spraying fuel all over the place, 2nd one same thing and the third one won't be in till thursday.

So my question is:
Is anyone else having problems with these primers lately?
Am I doing something wrong?

I am certain the fuel is not coming from around the copper crush washer, it is coming from under the black plastic cap/plunger.

I am considering priming the system and quickly plugging the whole for the primer and hoping that I never develop an air leak.

Any thoughts or comments?

Brian Carlton · #2 12-21-2007, 05:24 PM

Welcome to the forum.

Bosch is certainly known for quality issues.

Maybe they produced a bad batch of pumps.

It doesn't sound like you've made any errors in the install.

I've had the replacement on the SD for several years without any issues.

slm4996 · #3 12-21-2007, 05:28 PM

Seems like the next pump is going to come from a completly different warehouse before I get ahold of it. Maybe that means a differnent manufacturers lot.

A quick question to all thouse who have the new style pump.
What does you functioning pump sound like when depressed? Released?
My defective one, wich actually will prime the system, kinda hisses going in and gurgles coming up.

toomany MBZ · #4 12-21-2007, 06:38 PM

I've replaced four with the new Bosch, no leaks. Make sure you remove the old washer, before putting the new one in. And just make sure the fuel lines nearby are not causing the problem.
Haven't noticed any difference in sound.
You mentioned trying to prime the system and quickly plugging the (w)hole, that makes me think you are just going to use a plug in the primer pump location after you try to remove any air, is this correct? If so, I'll suggest against it, you'll need priming capabilities in the future.

slm4996 · #5 12-21-2007, 06:44 PM

I am thinking of just plugging the place that the pump should be. I know this is not ideal however I need my car back. I currently do not have any air/fuel leaking problems so as long as that doesn't change, assuming I don't run the tank empty

I should be OK. I am 100% positive that the leak is not coming from the washer/threaded area as I have wrapped a rag around the primer as the engine was running, to catch the fuel, and it is not bubbling out of that area. I should mention that on both pumps the leak was not a drip it is almost a spray of fuel.

toomany MBZ · #6 12-21-2007, 07:02 PM

Sounds like the spray is coming from just under the black cap. Is this correct? If so, it does sound like a faulty primer.
And yes, if you don't run out of fuel, you won't have a problem, yet when changing out fuel filters you'll have to lean on the starter. Speaking along those lines, continual cranking, with rest intervals, you'll eventually start...or should, anyway. That would be using the engine (starter) to send the air out via the exhaust valves, just takes a LONG time, a strong battery will help too.

Sbean · #7 12-22-2007, 02:42 AM

I've never seen one of the new primer pumps, so I don't know if it's possible to open it up and see if it can be repaired. This is my usual response when something doesn't work right. Steve

toomany MBZ · #8 12-22-2007, 05:36 AM

Doesn't look like it can be taken apart, without a sledge hammer!
http://catalog.worldpac.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=24D0DCENG2990BYHLD&year=1984&make=MB&model=300-CDT-001&category=All&part=Primer+Pump

slm4996 · #9 12-22-2007, 09:24 AM

If this last pump doesn't work I am going to disect it to find out why. I know tha I will never get it back together but now I just have to know why so many of these aren't working for me. It looks like inside the body of the primer, on the bottom open end, that there is a plastic insert that can be threaded out of the main body. I'll post back if the pics if I end up taking one apart.

ichbineinekrous · #10 12-22-2007, 06:47 PM

I've sold about 150 of these in the past year and have only had one come back due to a leak. My supply comes from Germany, there may be primer pumps coming from Mexico or Thailand made by Bosch. I havent been able to take one apart without destroying the spring mechanism, good luck.

slm4996 · #11 03-28-2008, 10:35 PM

OK very sorry for the long delay in answering, I ended up ordering a pump from a small local shop, got a bosch unit. Worked completly different from the start. I could actually feel the fuel being pumped and hear bubble into the fuel tank. When I started it up, no spray!

slm4996 · #12 03-28-2008, 10:36 PM

Next up, Valve adjustment. Any ideas on the wrench sizes needed for the 2 adjusting nuts?

Cr from Texas · #13 03-28-2008, 11:53 PM

My 617 primer pump is the original 25 years old, doesn't leak, never been used unless by the indy.

Why are they needed? If you fill the main filter when you change it, why would you ever need to use the pump? I tried mine to see if it worked and didn't know how to use it. You unscrew, lift, and pump, right? Mine wouldn't unscrew. I started to get some channel locks and use some persuassion but decided to leave well enough alone.
If I never use it, will it never leak or should I change it as a long trip precaution?

Charles

toomany MBZ · #14 03-29-2008, 03:40 AM

Quote:

Originally Posted by slm4996

Next up, Valve adjustment. Any ideas on the wrench sizes needed for the 2 adjusting nuts?

14mm, I use special bent wrenches I bought, many folks have bent their own, you my be able to re-use the gasket, but I have replaced mine.

toomany MBZ · #15 03-29-2008, 03:47 AM

Quote:

Originally Posted by Cr from Texas

My 617 primer pump is the original 25 years old, doesn't leak, never been used unless by the indy.

Why are they needed? If you fill the main filter when you change it, why would you ever need to use the pump? I tried mine to see if it worked and didn't know how to use it. You unscrew, lift, and pump, right? Mine wouldn't unscrew. I started to get some channel locks and use some persuassion but decided to leave well enough alone.
If I never use it, will it never leak or should I change it as a long trip precaution?

Charles

Good to hear yours doesn't leak.

One reason you have a primer pump is, were you to run out of fuel away from home, and don't have access to fuel to fill the secondary filter, you'll be able to get fuel to the IP without wearing out the starter or battery. Even when I swap out filters, I still prime a bit to get fuel to the secondary, because the new primary filter is empty also.

Yes, you unscrew and pump, being sure to tighten back down when finished.

If it's not leaking, you may get away with leaving it alone, just keep an eye out for leaks. Doubt it will start unless you use it.