95 E300D 606 engine noise

[Dinosaur]

1995 E300D non turbo ( 606 engine ) I need Tech Help.

127,000 miles with MB maintenance records.

I bought the car in September. It ran very good with no engine noises. I did a number of searches on this engine and found a list of things to check
Vacuum pump and special gasket, belt tensioner, tensioner shock (it was making noise ), Fuel O-rings ( they were all leaking ).

In October my wife lost coolant while driving the car to the store. The yellow light came on. She kept driving thinking yellow is caution, but when it turns to red stop. She informed me that night that the light came on and I might what to look at it. The car had lost all the coolant down to the bottom of the reserve container. Big leak. Oh, the PO had a jug of antifreeze in the trunk and said that the car had lost some coolant on a recent trip. Not much was used from the container.
I parked the car and did some extensive searches to find info on what I needed to do. I rented a coolant pressure tester and found that an aluminum pipe behind the fire wall, running from the battery side going to the driver side was leaking. I replaced it and pressured up the system and it held. I replaced the water pump, vacuum pump, serp. belt , belt tensioner pully, tensioner shock, fuel o-rings, fuel return lines, intake manifold gasket, trans. filter and fluid and pollen filter.
It took me until yeaterday to get all this done working in an unheated garage.
I fired the car up yesterday, I added 50ml of oil to the vacuum pump as I started the car. I took a while to start because of the fuel lines.
When the car started it made a banging noise in the front ( cylinder 1 area up towards the head).
It is loudest at idle, It seemed to get quite as I reved the engine but it made a loud bang and jerk while I was reving it. I turned the car off. I started it again and it still banged.
I forgot to mention when I was changing the vacuum pump I noticed that the timing chain was loose. This was after I drained the oil and the car sat for a month.
I did not do a measure of chain stretch because the CD manual does not indicate how to measure stretch.
Questions. Could it be a bad chain tensioner?( reading the manual it seems to be hydraulic)
Could it be an injector nailing? I did have to remove the injector lines
Is it a rod problem?
And what do I need to do to diagnose it? And fix it.
Also the fuel is still leaking and looks to be coming from the IP. The IP has a gasket in the middle.
Any Ideas would be appreciated.

Thanks Mike

[DR.DIESEL]

Were the grey plastic fuel line retaining clips all broken and pieces
missing? Sometimes these little buggers can fall down into the open intake ports when you lift the intake manifold off.
Plastic and valve seats do not mix.
Usually it is just carbon that is keeping the valve from seating
completely. The OM606 valve springs are very light and don't
have the power to crush carbon down quickly.
You have 2 choices, Take the intake off and inspect all the ports
for debris. Or just rev that puppy up to 3500-4000rpm and try to
blow the carbon away from the valves.
Best of luck.
Dr.D

[Dinosaur]

Dr.Diesel,
Thank you for your quick reply. I did read on one of your previous posts that the plastic clips could fall into the intake on the head when removing the manifold. I watched for this and look into the ports with a light before installing the manifold. I even order 7 new clips and replaced the old ones. The center intake ports had about 1/8" of carbon build up and some of them were wet. I had to replace the rubber pcs. that attach to the intake manifold also. Most of the holes were blocked. When I scraped some of the carbon away(like black goo) form the intake ports some pcs fell into the head. But I really tried to keep it out.
What about the timing chain being loose?Does that impact the noise I heard?
How can I check the timing chain stretch? They changed the oil every 5-7K miles at the dealership.
Also does the IP ever leak from the middle gasket or am I missing a leak up by the heat exchanger at the head?

Thanks again

Mike S.

[psfred]

Oil in the vac pump? What for? I assume this is in the procedure?

I'd not put liquid in a gas type pump, it will knock like crazy until it all blows out (if you don't fracture the pump first).

Loud clank can be a loose chain from a failed or depressurized chain. I'd pull the valve cover and check the tensioner -- it must be diffucult to push the rail back against the tensioner with engine recently run. Oil will drain out on sitting, so the chain will slap some on startup if it has significant wear.

You can check the chain stretch by lining up the marks on the cam tower and thust washer (not sure of location on the 606), the reading the degrees past TDC on the crank pulley. Must be less than 8 or replace chain.

Did you replace the o-rings on the pressure valve holders on the IP? If so, did you use a new pressure valve holder copper seal? If not, you may have a leaking seal -- this will cause serious injector knock (sounds like a hammer on the block) on the affected cylinder, along with excess vibration and power loss.

Peter

[Dinosaur]

Peter,
Thanks for your input.
This vacuum pump is the one that fails without notice and pcs. fall into the block. I had searched on the forum and found that some owners had had this problem. MB designed a replacement gasket that is intended to keep the pcs. out of the block. When I pulled the old vacuum pump that appeared to work fine, I noticed that the bearing was stiff. 127K miles it was probably ready for a change.
I bought a new vacuum pump and the installation instructions said to add 50ml of engine oil in the inlet as soon as the engine starts, then immediately connect the vacuum line. ( regarding the gasket update, I first just tried to buy the updated gasket twice and both times I was sent the original type. When I removed the old pump and noticed the bearing was stiff I ordered a new pump and it came with the updated gasket.

I think what you ment was a depressurized chain tensioner. I have the CD manual and it shows that the tensioner must be pumped up with oil before inserting. It does not indicate if the tesioner can be rebuilt. I did notice the chain was loose both where the vacuum pump was attached and also at the cam gear while I had the valve cover off.
I will remove the valve cover again and check the chain stretch and tensioner. I had to remove the timing indicator when I replaced the water pump. I marked it and tried to set it in the same stop. How else can I fine TDC?

I only changed the o-rings on all the clear fuel lines, prefilter and filter. I will look at the CD regarding the IP and check for o-rings and washers(the IP seems to be leaking from some where.) The funny thing is this car ran smooth and fast when I first bought it, but it leaked also leaked a lot of fuel. The two plastic pans that I removed under the engine and transmission were soaked with fuel and trans fluid.
Again I appreciate all your help. I will start on these suggestions when it warms up some.

Thanks,

Mike

[MrCjames]

psfred

Yes, it is in the procedures. Vacuum pumps are mechanical and they require lubrication after installation in order to prevent galling of the pumps cylinder, piston, & sealing rings. Manufacturers usually supply “Installer Instructions” for a number of reasons, “Reliability” being the most important. This ensures that the replacement item being installed will live up to, or exceed the consumer’s expectations. You would not start a new engine without priming the oil pump/system and since this is a vacuum pump/engine it warrants the same precautions.

[psfred]

TDC can be located by removing the cam and a valve spring on #1 cylinder, attaching a long through dial indicater to the top of the valve, and turning engine around TDC until the indicator stops moving. Not for the faint of heart. YOu can also pull the #1 prechamber and do the same thing (carefully!), but that's a big pain, too.

I'm used the the older 615/617 pumps that are directly lubricated with engine oil in the chain case (or have rubber diaphrams), no oil in those.

I would certainly ascertain the reason for the knock before running the engine -- rotate the engine around by hand and see if you can find out what clonks. If it binds or refuses to turn, you may have jumped the timing chain a tooth on the cam gear, causing the exhaust valve to contact the piston on the exhaust stroke. You will find out when you check the chain stretch.

See if the fuel leak is from around the pressure valve holders on the IP -- were the injector lines screw on. There is an o-ring on the holders that goes bad and leaks.

You may also just have some air in the IP, causing late or intermittant injection on one cylinder -- if so, this will clear when you drive it. You can check for this by loosening the injector cap nuts one at a time -- if the knock stops, and starts again when you re-tigthen, you have a injector problem of some sort. If not, it's not fuel related.

Peter

[prb51]

For the fuel leaks. Check the right rear side of the engine block at the cam cover for fuel wetness. There is a drain built into the cam cover there to allow fuel to drain when the IP return lines fail. Check the injector wells for fuel buildup. If they are wet change the return lines.