We need a more detailed hypothesis as to where that fuel is leaking from. I'm not real familiar with the lift pump but I'm thinking that the only possible places for the fuel to leak is either from the primer pump or from the fitting where the fuel line attaches to the pump. Is there another place it can leak? It could be that the line from the primary fuel filter to the lift pump is bad and the lift pump is sucking in air rather than fuel. I can't remember another instance on this forum where the lift pump failed and the indication of that failure was a leak. Can anyone else recollect such a case?

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Kerry,

I'm probably not describing the part correctly, and I am a newbie at this. The manual primer pump is attached to a small device which has two feed lines on it. This is then bolted onto the side of the IP with three 10mm nuts.

My primer pump is shot, and I was told, or I thought I read some where that this could also mean that the fuel or lift pump was on the way as well, or could be.

I'm thinking that it's leaking, as I've never touched it since I've had it and up until recently, it's worked without incident. Putting all the pieces together, I now know that it must have been leaking for at least a week or two as of the sheen on my driveway which I talked about in the last post.

When I placed my hand underneath the fuel pump, I felt several large drops of fuel that had attached themselves. This location is close to the drivers side engine mount, I assume that it dripped from the fuel pump to the engine mount.

I usually drive this car to work as my DD, but my thought....and it might not hold water...is that with the extra weight of two more people and their luggage in the car, going up my hill by my driveway was too much for a weak pump and it sputtered out on me.

Maybe it's a stretch...I don't know. I'm always open to your thoughts.

Thanks,
Mike

I think the leak is the cause of the problem. The issue is: Where is the leak coming from? I'm not aware of how the pump itself can leak. Does anyone know if it can?

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

The manual primer pump can leak if it is not locked tight enough. I have to use pliers to lock the primer pump on my car.

__________________
'85 300D Cal 280,000 miles
'14 GLK 350 60000 miles

I'd be scared of breaking the plastic handle with pliers!

He hasn't mentioned a leak while he's pumping so it doesn't seem like it's the primer pump.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Yes it can break. Just be careful. Some 116s have metal handles.

__________________
'85 300D Cal 280,000 miles
'14 GLK 350 60000 miles

My primer pump has the off white plastic handle. It as well as the fuel pump look original to the vehicle.

I just got my new BOSCH fuel pump with the new style primer pump and when I pushed down on the primer pump handle..it moved some air. I really did need a new one. I'll report back tomorrow on how it works (or not).

Mike

Gents,

I just wanted to post back with my results. I got the old pump off and the new one installed in no time. Really was fairly easy...just took my time so I didn't lose any of the nuts and washers.

Once I got the new one on, it was time to pump and purge the system per the MB tech manual.

I had to crank it awhile...but it finally caught and runs well. I noticed that when I just began to push down on the accelerator there isn't a hesitation now like there was before...that might just be my imagination.

Anyway, I want to thank you all for giving me your expert advice. I hope this post helps someone.

If anyone has any questions in the future..feel free to PM me.

Happy New Year to you all,
Mike

Good news. Can you do any forensic analysis to figure out exactly what the problem was? Where was it leaking?

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Kerry,

My gut tells me that if I had just replaced the primer pump I would have been OK. I didn't want to take the chance and be out a DD so I decided to do the fuel pump as well.

My guess would be that the primer pump was the cause of my air leak and then when I couldn't purge the air like I was suppose to, I ran into the above mentioned problem.

I did notice and I can post some pics that the old pump had some wearing (striations) in the metal "ears" that hold the "lobe" that goes around inside the fuel pump. The new one did not have these marks. Otherwise the old pump looked good.

My curiosity is now demanding that I get a new primer pump and place it on the removed old fuel pump and see if that will move the same air as the new pump. If so, I have a "spare".

I never could locate the leak, but again, my thinking is that it was the primer pump seal/gasket went out. I've checked several times now that I've run it at speed for while, and I don't see any more fuel, and when I check the whole pump with my hand, I don't feel any liquid. So here's hoping I got it.

Mike

That would be odd if that is the case. Usually what happens when the primer pump fails is that fuel comes out around the shaft when it is pumped. At least, that is what most people report. Since nothing was happening, it suggest a different problem or an unusual twist on the primer pump problem. Was the lift pump tight against the IP when you began to remove it or was it loose?

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Did you screw the white knob (of the old primer pump) in clockwise after priming? If not, air will get in. You did not mention spilling lot's of fuel with the old primer pump, which is normal so the old pump may have been bad, or there was too much air in the system and it was not strong enough to push the air out first.

__________________
85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

Kerry,

I did see some fuel around where the primer pump fits into the fuel pump. The pump was tight, and I do believe it was the original.

Funola-Yes the white knob was screwed down tight. I'm know the primer pump was bad, as it didn't move any fuel at all. Once I got the new one on, I removed all the air fairly quickly.

Since I've replaced it, no leaks and she runs well.

As an aside...I had to replace my battery today as all that cranking and it's cold here (teens to high 20) finished it off.

Mike

Here's a relevant post from someone with a lot of experience with the pumps:

Lift Pump Rebuild...

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13