What wrong, head pic 99TD - PeachParts Mercedes-Benz Forum

oldwheels · #1 07-22-2008, 07:38 PM

See pics of head, block and gasket.

Problem, low compression cyl 1, leaking down. Oil consumption up some.
Take a look and give me your opinions. Notice cyl 6 spary nozzle is black.

oldwheels · #2 07-23-2008, 08:19 AM

bump cause I can. Falsely important

vstech · #3 07-23-2008, 01:44 PM

those pics don't really say much besides #6 wasn't getting hot enough to burn off the soot. probably from the low compression...

#4 07-23-2008, 01:47 PM

I agree with the above. #1 had some liquid in the combustion chamber (everything is steam cleaned of carbon) and #6 wasn't burning very hot.

Post close up pictures of the #1 and 6 head and piston.

vstech · #5 07-23-2008, 02:24 PM

I also notice that #1 has very little gasket seal around the lower portion of the pic... no water there, but you never know...

barry123400 · #6 07-23-2008, 03:06 PM

A head gasket might get your #1 problem solved. Before that I would have the head critically checked by a decent shop for flatness and cracks. Primarily the number one chamber for any evidence of cracks.

Also since there is a slight chance a crack is in the valve feed passage. A head pressure check would be even better. Nothing like spending other peoples money though.

The only thing really certain is that coolant was getting in there somehow.

You did not post a head gasket picture of both sides. A close up of the #1 area would be best. It might help if you do and might not.

Number_Cruncher · #7 07-23-2008, 04:49 PM

Carefully check the inlet valves while the head is off.

Make sure that they all sit at the same height in the head - on mine, the inlet valves in No 6 sat a lot lower than the others.

Also check that when open, the inlet valve rim isn't sharp - there should be a decent radius which blends into the conical valve seat. If the valve is worn, this will become a sharp edge.

On my OM606, the inlet valves had sunk so far that the hydraulic tappets were fully closed, and I was losing compression on No 6. New inlet valves, and new seats for cylinders 5 and 6 were required to correct the fault.

Among the giveaway signs of this was dry sooty deposits in the inlet ports of Nos 5 and 6, instead of oily deposits.

Edit: forgot to say that WINGAS of this forum has also had similar problems with his OM606, search for his thread to read all about it.

oldwheels · #8 07-24-2008, 05:53 PM

I have the head apart now.
No. 1 has extra wet soot all the way thru the intake track. Why no 1 is a good question.

No 6 is black. , I had the injectors just redone, 3 miles ago. No 1 was marginal, most were fair and couple marginal.

No 1 cyl was not idling. Was runnig at RPM.
I did compression check. on cold block
320 psi and leak down pretty quickly
No 4 was 440 psi.

I didn't do all the cyl. Now I wish I did.

I also didn't put in squirt of oil to see if this bumped it.

NO. 1 gasket may have been weaping a little. Examining with magnify glass yielded no visual scorch or weapage paths.

No 1 cyl has extra soot on intake valves and port for entire length. This is a mystery. See pics og gasket.

Prechambers look okay with no weird ness.
The valve seat don't show signs of being burnt. There was soom soot particles on no 1. Which my be the leak of pressure.

I'm measuring bores on block tonight.
So far no smoking guns or obvious culprit. I'm on a mission from Germany. Fukenknocken to my brain.

Number_Cruncher · #9 07-24-2008, 07:09 PM

>> The valve seat don't show signs of being burnt.

Although very badly worn, the seats on my engine didn't appear burnt. The valve and seat had worn so the valve sunk into the head. The form of both the valve and seat was changed; on the seats, there wasn't a well defined conical seat form.

oldwheels · #10 07-24-2008, 09:18 PM

After getting out all the valve I'm send the head away. The exhaust seats are pitted and the ex valves are pitted. Rather an ugly scene. For 130k engine I'm surprised.

michakaveli · #11 07-24-2008, 10:51 PM

Quote:

Originally Posted by oldwheels

After getting out all the valve I'm send the head away. The exhaust seats are pitted and the ex valves are pitted. Rather an ugly scene. For 130k engine I'm surprised.

Is this a recently acquired vehicle? Did you check the coolant to see if it is milky at all or "odd" other than the off orange color?

oldwheels · #12 07-25-2008, 08:21 AM

The coolant was perfect. Absolutely nothing in it. I drained it when the head came off.

Cervan · #13 07-25-2008, 10:09 AM

i would suggest taking it a machine shop and having it tested for straightness and having it pressure tested/xrayed for cracks. level check should be free, and the pressure test should be about 30$ but its well worth it..

For the leakdown test, check the cylinder walls very carefully if they look good, then its in the head. carefully check all of the valves make sure the seats look good on both the valves and the head. If everything checks out, lap the valves very well and throw it back together.

EDIT: ah, that would show why your leakdown showed crappy results. Alluminum and diesel just doesnt mix..