Fuel Check Valve on 87 300TD - PeachParts Mercedes-Benz Forum

frankstallone · #1 03-05-2008, 05:14 PM

I posted a thread about purchasing a 1987 300TD and I got into discussion there and got some great feedback on what to look for. I am not posting this to see if anyone has ever replaced the check valve inside the fuel injection pump?

The car has starting problems and the MB Shop he brought it to told him it was the check valve which on cold starts does not hold fuel pressure properly.

The MB Mechanic also told him that it threads into the injection pump and can be done with the pump on the car. Now this is where I admit I do not have enough hours looking at this engine to know whether or not that is BS or possible; or a pain to do even attempt.

If you have any experience great fill me in on whatever you know. He said he purchased the check valve, it cost him $60 and it is sitting in the glove box.

Thanks for reading!

TMAllison · #2 03-05-2008, 05:24 PM

See banjo bolt #637. Suspect that is what the mech is talking about.

Never done it. Don't think it is too difficult; just tight quarters.

http://detali.ru/cat/oem_mb2.asp?TP=1&F=124133&M=603%2E960&GA=722%2E317357&CT=M&cat=503&SID=07&SGR=120&SGN=04

gsxr · #3 03-05-2008, 08:30 PM

Terry is correct, item 637 is the check valve, on the back side of the pump.

However I doubt that is the cause of any starting problems. I've never heard of one failing, or being the cause of hard starting. Probably 90% of starting problems on these engines are due to glow plug issues. The other 10% are an assortment of gelled fuel in arctic temps, fuel supply problems, weak battery, plugged exhaust, and other oddball problems.

On a side note, if you are looking at buying a 1987 300D/TD, you might want to read this "buyer's guide", if you haven't yet seen it:
http://www.w124performance.com/docs/mb/articles/124.1x3_buying_tips.txt

Bio300TDTdriver · #4 03-05-2008, 08:33 PM

Quote:

Originally Posted by gsxr

Terry is correct, item 637 is the check valve, on the back side of the pump.

However I doubt that is the cause of any starting problems. I've never heard of one failing, or being the cause of hard starting. Probably 90% of starting problems on these engines are due to glow plug issues. The other 10% are an assortment of gelled fuel in arctic temps, fuel supply problems, weak battery, plugged exhaust, and other oddball problems.

On a side note, if you are looking at buying a 1987 300D/TD, you might want to read this "buyer's guide", if you haven't yet seen it:
http://www.w124performance.com/docs/mb/articles/124.1x3_buying_tips.txt

If only I had read it before I bought.

frankstallone · #5 03-06-2008, 11:37 AM

gsxr: thank you I have been reading through it slowly today and it will help me with my inspection list I am putting together for when I get out here. So far there are a lot of good PM items on the list!

TMAllison · #6 03-06-2008, 12:29 PM

Like GSXR, I believe the check valve to be a VERY low fail part (its a mechanical valve, not much that can go wrong with it) and while repalced by some I doubt is the root of the problem typically.

As I am remembering your other post, the hard start issues should be related to the leak reported at the delivery valves on the top of the pump.

frankstallone · #7 03-11-2008, 06:31 PM

I am thinking about this logically and the guy said the car had a slight gas leak; a slight fuel leak would cause a loss of pressure which is what his MB Shop told him the reason for the cold start issue.

No pressure = Hard cold start

I am thinking it is because of a leak I suspect @ the fuel pump.

Are the fuel pumps in the gas tank for this car?

How hard of a job is it to replace?

Thanks for reading!

gsxr · #8 03-11-2008, 06:47 PM

The fuel pump is a small mechanical item, bolted to the side of the main inline injection pump. I attached a photo below of the fuel pump. If you can find a fuel leak, fix it. If the hard starting persists, it's probably not from the fuel. I'll say it again, has the glow system been tested thoroughly?

frankstallone · #9 03-16-2008, 12:16 PM

gsxr: I just got the car back and the fuel leak is coming from one of the injectors on the injection pump. I am going to clean it off w/ some engine bright (maybe take some pics) and see how hard it is to replace what is bad. I am not sure if it is seals or what. Go Worldpac for a good picture =)

Cheers!

TMAllison · #10 03-16-2008, 03:17 PM

Fairly painless. Need special socket to remove Delivery valve holder and then replace oring and crush washer. If you do one, do all.

OM60_series IP delivery valve reseal

frankstallone · #11 03-16-2008, 06:32 PM

TMAllison: I snapped some HD pictures with my Camera for you guys to get an idea of where it is leaking from (fairly bad too)!

I think it's seals too, but again for some reason this guys MB Shop said it was the check valve (drats, forgot to take a picture of that for you guys... ill do that later).

Either way this picture shows it best:

Here are some other pictures, made them click able because of their size.

... So I need a special tool to remove these I presume like Terry was saying? The car is leaking bad enough that I can not drive it until that is fixed.

Also the transmission changes gears pretty hard and I am going to start a new thread asking if there is a 'throw back' cable like there are on Honda's to change how hard the transmission changes gears.

Thanks for your help guys!

- Frank

frankstallone · #12 03-16-2008, 10:13 PM

I found the check valve from the diagrams (don't ask me how I missed it) and although it looks cruddy it doesn't look like its the main leaking issue.

gsxr · #13 03-17-2008, 01:24 PM

The leak in the photos is for the delivery valve seals. You need the special socket, new O-rings, and new crush washers. There is a specific torque procedure for these... 30Nm, release, 30Nm, release, final torque of 30-35Nm. You must have the area surgically clean while doing this job, not a trace of dirt of dust can enter the IP, injector, or fuel lines. The intake manifold should come off to allow room to work, and to allow room to get the torque wrench in there. If you over-tighten the barrel, you can get nailing, or warp the pump body...so be careful. Better to be slightly under-torqed, if in doubt. A photo of the special socket is here. It's about $35 from most dealers.

The tranny shifting hard is due to vacuum, not a cable adjustment. The cable adjustment tells the tranny when to shift, not how firm to shift. The vacuum signal tells the tranny how firm (or soft) to shift. If there is ANY vacuum leak, it will shift hard. First thing is to trace every single vacuum tube and rubber fitting and check for leaks. After that, adjust the VCV (vac control valve) on the side of the IP per the FSM procedure. If the ALDA is not adjusted properly, that will also cause a late, hard shift because you're using a lot more "pedal" than it should need.

frankstallone · #14 03-17-2008, 05:12 PM

gsxr: thank you for your amazingly detailed explanation of the problem! You don't happen to live near Central Jersey and are possibly in the need of some extra cash are ya? haha j/k, thanks for all the information I really appreciate it!

I can't wait to get this leak fixed so I can drive this thing w/o a mask on. I love the smell if diesel but this leak will make you dizzy.