W115 Owner Advice Needed: Buying a 1976 240D - Page 4 - PeachParts Mercedes-Benz Forum

Screwdriva · #46 06-25-2019, 02:43 PM

Quote:

Originally Posted by vox_incognita

I don't know how Monark primer pumps look like but newer Bosch units are just fine (made in Austria).

Mann-Hummel , Knecht-Mahle and Hengst used to offer aftermarket plastic mesh oil filters(which is your full-flow oil filter...it is not a "pre-filter").

Thanks for the tips Vox - pictures of the filters and primer pump (note the OE metal finish look) attached:

vox_incognita · #47 06-25-2019, 04:33 PM

Yes...the plastic mesh is Mann-Hummel o5001 which is not available anymore as an aftermarket part (and both Hengst and Knech-Mahle list their analogs as no longer available ).

You'll need to remove the lift pump to give the hand priming pump a nice snug fit.And add oil to correct level in IP again after reinstall. Gasket lift pump to IP - A0000911780 .

If anything else needs changing on the lift pump(check valves, o-rings) it can be done easily and for cheap (parts still available from Bosch).

marco5 · #48 06-25-2019, 10:26 PM

I just wanted to say consider checking the timing chain and/or just replace, especially in a W115.

My first diesel was a 1976 240D and it had 1 timing chain, unlike the newer W123 which started in 1976/1977-1985, which has a double chain.

I blew/skipped the timing chain my second month of owning it and ruined the valves and sadly scrapped the car due to the car also having severe rust.

Screwdriva · #49 06-26-2019, 05:51 PM

Will inspect the chain at your suggestion. Guessing I should be looking for slack?

Was just told that both front calipers were seized and that I should replace the bearings as well. There goes another grand! Part numbers for reference

Front brake calipers: Part #s 001-421-82-98-MBZ (Right) and 001-421-81-98-MBZ (Left)
Wheel Bearing Kit: # 123-350-00-68-MBZ

vox_incognita · #50 06-26-2019, 06:13 PM

Reman.calipers should be readily available in UK.I guess they'd be less than GBP 70 for a caliper . They were used on many models for >15 years.
OEM Rep.kits (made by ATE) are probably GBP 30 per caliper. Aftermarket kits (ATE,FTE, FrenKit) are even cheaper. Repair is easy (if the pistons are not solidly frozen to the bore).
Wheel bearing kits are available from SKF and FAG and Timken probably.
I would not necessarily buy these items from the dealer.
I saw in another thread a photo of a dealer clutch pilot bearing box stating "made in Portugal" - I bet it was a FAG bearing that costs nothing as aftermarket part.
Look up the SKF and FAG automotive catalogs for kits first if the dealer price is unpleasant.

Screwdriva · #51 06-27-2019, 05:28 PM

There is a $20 difference between the MB bearing kits and either SKF or FAG kits. Cost aside, Timkens (in my experience) suffer from rampant fakes/ imitations. This is why I went with MB supplied kits.

I thought about rebuilt calipers as an option and struggled to find a source for them here in the UK. Repair kits are cheap but the labour to rebuild them would come close to a new caliper sadly.

vox_incognita · #52 06-27-2019, 07:08 PM

Search the part numbers of the calipers without the dashes.
Like 0014218198 or 001 421 81 98
on amazon.co.uk or elsewhere.

https://budweg.com/catalogue/?search&brand=MERCEDES&model=240&engine=2.4&fromYear=1973&fuel=D&model_code=

Etc.
ABS is a Dutch brake and hydr. remanufacturer...

These are all on original ATE units.

But if the price is not that off from dealer's (like with the wheel bearing kits) ,go with MB's.

Screwdriva · #53 07-17-2019, 10:28 AM

Drained the fluid from my injection pump today. Strangely, it didn't appear like it was oil. It had the consistency and colour of Diesel but without any of the smell. It could have been an additive but there appeared to be nothing with oil like texture or consistency in the pump. We drained the fluid entirely and replaced it with the Liqui Moly MOS2 10W-40 oil for now.

Any thoughts on what happened?

t walgamuth · #54 07-17-2019, 02:45 PM

I think you'll find the injection pump is oiled from engine oil on a 76.

Screwdriva · #55 07-17-2019, 03:14 PM

Quote:

Originally Posted by t walgamuth

I think you'll find the injection pump is oiled from engine oil on a 76.

Its a separate supply of oil (has a red cap).

vox_incognita · #56 07-17-2019, 05:31 PM

Well there are several plausible scenarios:
-IP has not been serviced for a while, fuel diluted the oil
-Somebody serviced the IP with some unknown low-visc. oil (and then after decades I would not expect the proper smell in an open system)
-Somebody serviced the IP with diesel fuel (all kinds of free thinkers wander this world...)
...or a combination of the above

About fuel diluting the oil:
-it may be the result of normal IP elements leak-off(that is why IP has a leak tube on the right side and the IP oil should be replaced)...
-or fuel may enter the IP internals sneaking thru the lift pump plunger rod/bore and o-ring.

Since on this IP the oil in the cam space is not pressurized it would be easy for the fuel to dilute it if the o-ring (or/and the plunger rod/bore)is worn-see fig.07-4/24,"discharge and suction stroke".

The opposite path (IP oil entering the lift pump pressure space) on your pump is also possible but it will be waaaay less pronounced compared to IP's that get lubricated by pressurized engine oil. Since you've put the gray/black MoS2 oil in it would be very easy to detect.

Anyway, lift pump is very easy to service and parts are readily available and cheap from Bosch(o-rings nowadays green,Viton)

Did you collect what came out from the IP (volume,etc.?)

Check out these graph for fuel system setup and lift pump operation(not 1:1 but give you proper idea how they operate) :
What does the cigar hose do....

moon161 · #57 07-18-2019, 08:33 AM

Quote:

Originally Posted by Screwdriva

Will inspect the chain at your suggestion. Guessing I should be looking for slack?

You'll be looking for wear or stretch. The tensioner should take up the tension and leave IIRC, not much if any slack. As the chain wears it gets longer and so does the pitch between links. In usual cases, the cam is a couple degrees behind where it should be, in extreme cases (way past due/never changed the oil) the teeth on the sprockets will start to look like shark fins.

https://www.peachparts.com/Wikka/OM617TimingChainStretch

Screwdriva · #58 07-18-2019, 04:22 PM

Quote:

Originally Posted by vox_incognita

About fuel diluting the oil:
-it may be the result of normal IP elements leak-off(that is why IP has a leak tube on the right side and the IP oil should be replaced)...
-or fuel may enter the IP internals sneaking thru the lift pump plunger rod/bore and o-ring.

Since on this IP the oil in the cam space is not pressurized it would be easy for the fuel to dilute it if the o-ring (or/and the plunger rod/bore)is worn-see fig.07-4/24,"discharge and suction stroke".

The opposite path (IP oil entering the lift pump pressure space) on your pump is also possible but it will be waaaay less pronounced compared to IP's that get lubricated by pressurized engine oil. Since you've put the gray/black MoS2 oil in it would be very easy to detect.

Anyway, lift pump is very easy to service and parts are readily available and cheap from Bosch(o-rings nowadays green,Viton)

That would explain it - the lift pump aka hand primer pump was entirely worn (factory supplied white cap Bosch). It was leaking alot of fuel. I just replaced the pump + washer that came supplied with the new pump assembly.

I replaced it with a Monark hand pump that comes equipped with viton seals (in my view, the best looking German replacement available). Based on your explanation, I believe this will address the issue of oil dilution.

I wonder if this is the reason the car would stall when shifting out of 2nd to come to a stop?

vox_incognita · #59 07-18-2019, 04:54 PM

Changing the hand primer pump will only address air-in-fuel ingress and leakage.
It has no relevance to fuel-oil dilution(this will be remedied -if needed -by changing the o-ring of the lift pump plunger rod).

It may or may not have effect on stalling when coming to stop. In extreme cases overfilling the IP oil sump would hinder the proper movement of the diaphragm(and the IP rack)but I don't think this was the case. Does it still want to die when you switch to neutral coming to stop?Did you check/adjusted everything from earlier posts?

It is easy to bring back the fuel supply system to in-spec condition. Pretty much every part is widely available and easily repairable.
You see the fuel must enter the low-pressure fuel chamber of IP at a certain pressure and air-free(properly set by-pass/overflow valve and air-tight supply system are a must).

Screwdriva · #60 07-18-2019, 06:49 PM

Cheers Vox. Is there a guide to locating/ replacing the plunger rod o-ring?

I haven’t driven the car yet as it is going through a mini restoration. Will report back in 7-10 days.