OM603 Installing new head gasket on Sunday - Page 3 - PeachParts Mercedes-Benz Forum

ah-kay · #31 11-24-2012, 06:40 PM

Quote:

Originally Posted by Brian Carlton

You have to address this engine as cheap as you possibly can........or call it terminal and replace it.

I never over-repair. The 300SDL is a rust-free California car with original shiny paint. 9 out of 10 inside and out. I like tinkering so this is a challenge to me. I am going to replace the rings as the oil ring is broken. Never done engine work before so everything I do is for the first time.

I am going to look at the valve and seat and take it from there. My hope is to bring compression on cyl # 2 up to at least 250+ and button it all together and drive it. Hope I can get another 50K out of it and then rebuild/replace the engine.

So you do not recommend honing cyl #2?

GregMN · #32 11-24-2012, 08:39 PM

Hone #2. Don't try to get the scratches out by honing.

Look up how to seat rings for your first drive.

Consider a cheap, temporary, water injection system to attempt to de-carbon the rest of the piston rings and help seat the new ones.

Then, if it starts well, runs good, and doesn't burn too much oil... just drive it and don't worry about doing another compression test.

ah-kay · #33 11-24-2012, 08:56 PM

Quote:

Originally Posted by GregMN

Hone #2. Don't try to get the scratches out by honing.

Do not understand this. Hone or not hone. Or hone it but do not get the scratches out? half and half?

Brian Carlton · #34 11-24-2012, 09:13 PM

Quote:

Originally Posted by ah-kay

So you do not recommend honing cyl #2?

If you're changing the rings, you probably should do it at that mileage. The original honing marks are probably gone by now. Don't even hope to get those scratches out, however. The use of the hone is only desired to provide a cross hatched surface to seat the rings properly.

If you overdo it with the hone, the cylinder grows in size by more than the FSM allowance. That will cause all kinds of issues with excessive oil consumption.

mplafleur · #35 11-24-2012, 10:27 PM

If you re-ring the piston, you have to hone to some extent. (if there is no cross hatching evident) You have to hone to get the tiny scratches needed to hold the oil needed for the rings to ride on after seating, but you don't want to make the bore any larger.

If there is no cross hatching, the new rings will never seat and the glazed bore will cause excessive oil consumption.

Don't use synthetic oil to break in the engine. It is too slippery and will likely cause the bore to glaze.

635CSi · #36 11-24-2012, 11:46 PM

Quote:

Originally Posted by ah-kay

Need some ideas here. I installed the head and torqued everything down. Before I put everything together, I decided to do a cold compression test and the result is NO good.

cyl 1 - 300
cyl 2 - less than 50.
cyl 3 - 350
cyl 4 - 200
cyl 5 - 300
cyl 6 - 100.

The engine was running but missing at idle. I should have done a compression test first before I pulled the head. I did not so I do not know what the reading was like. I did compression test on this engine 1 year ago and the result was good. I have a few questions:

1) How can cyl 2 be so low? The head is bad or the block? Put 2 spoonful of oil thru the inlet valve and the compression goes up a little bit to about 80.
2) Anything I can check before I pull the head again?
3) I have another #14 head. It is from the car where the oil pump chain snapped and buggered the engine. It is a good head as the car was running. Shall I try to install this head?
4) Can I reuse the Head Gasket? It is torqued down but never used so to speak.

Any help is appreciated.

May I add that piston 1, 4, 5 and 6 are also a bit concerning, more so 2, 4 and 6 since the specs are:

Specified Compression Value 26 - 32 bar (375 - 465 psi)
Minimum Compression Value approx. 18 bar (260 psi)
Permissible difference between cylinders 3.0 bar (43.5 psi) max.

Whiskey Tango Foxtrot · #37 11-25-2012, 11:03 AM

I'm no expert, but as the previous members have stated there is really no short cut in achieving the necessary tolerances, crosshatch, correct cylinder wall RA etc...
but many people have bottle brush honed cylinders or re-sleeved and thrown in a new set of rings and called it a "re-built" engine.
Maybe works for a while...maybe not. Good luck.

barry12345 · #38 11-25-2012, 06:24 PM

Turn the head uposide down and introduce some thin liquid around the valve seat recess area. Just to make sure the valves are seating well. Only takes a minute with the head off usually. I always used to check a redone head when I got it back prior to installing.

ah-kay · #39 01-02-2013, 03:27 PM

I am trying to put the head back. I did a minimum 'ring job' on the car. I took the oil pan off, pushed pistons up. I honed the cylinders, replaced the oil pump chain and the pistons rings. I strapped the cam sprocket to the timing chain at all time when I took out the head. I have since rotated the cam many times with the head off, rotated the engine a bit to get the pistons out.

My question is:

It is OK just to put the sprocket back on the camshaft with the key aligned. I think the cam rotates 2 times relative to the crank ( correct ?? ). Did I mess up anything when I rotated them independently? Any info is appreciated.

barry12345 · #40 01-02-2013, 09:48 PM

Yes and no. Get the tang showing in the injection pump port with the crank timing at 14 degees past top dead centre I believe on these engines but check in the archives. . If the tang is not there turn the engine over one more turn with the injection pump moving along as well. If tang in injection port is now visable. Then get the number one cylinder valves pointing upwards more or less at a 45 degree angle for each lobe. Crank back at zero. Using the closest way to get it there.

Position head and install cam sprocket. If tang is not visable in either senario you have lost the injection pump timing so just get the head and crank marks right. With the number one cylinder valves again generally pointing upward. Get a locking device.

Set the crank at the fourteen degrees. Back the injection pump out and get the tang locked down. Then reinsert the injection pump and you should be timed properly.

ah-kay · #41 01-02-2013, 10:04 PM

Quote:

Originally Posted by barry12345

Yes and no. Get the tang showing in the injection pump port with the crank timing at 14 degees past top dead centre I believe on these engines but check in the archives. . If the tang is not there turn the engine over one more turn with the injection pump moving along as well. If tang in injection port is now visable. Then get the number one cylinder valves pointing upwards more or less at a 45 degree angle for each lobe. Crank back at zero. Using the closest way to get it there.

Position head and install cam sprocket. If tang is not visable in either senario you have lost the injection pump timing so just get the head and crank marks right. With the number one cylinder valves again generally pointing upward. Get a locking device.

Set the crank at the fourteen degrees. Back the injection pump out and get the tang locked down. Then reinsert the injection pump and you should be timed properly.

I have never worked on diesel engine timing so I am a newbie so to speak. How could I have altered the timing? The timing chain was on the car wrapped round the IP sprocket at all time, not a tooth was moved. IP was not moved. The camshaft sprocket was strapped to the chain at all time. If I put everything together using the sprocket key as a guide then the camshaft and the IP should be back to what it was.

Is that correct?

Brian Carlton · #42 01-02-2013, 10:16 PM

Quote:

Originally Posted by ah-kay

The timing chain was on the car wrapped round the IP sprocket at all time, not a tooth was moved. IP was not moved. The camshaft sprocket was strapped to the chain at all time. If I put everything together using the sprocket key as a guide then the camshaft and the IP should be back to what it was.

Is that correct?

That is correct.

The fundamental assumptions are that the relationship between the chain and the cam sprocket has not changed and the engine has not been rotated without the chain.

ah-kay · #43 01-02-2013, 10:19 PM

Thanks Brian. This is the answer I am looking for.

ah-kay · #44 02-15-2013, 05:38 PM

Quote:

Originally Posted by ah-kay

cold compression test and the result is NO good.

cyl 1 - 300
cyl 2 - less than 50.
cyl 3 - 350
cyl 4 - 200
cyl 5 - 300
cyl 6 - 100.

The car is back on the road now and has done 400 miles. No blow-by to speak of, idle smooth, no smoke. The engine seems to be a bit noisy but it could be my imagination. I managed to resurrect a nice rust-free CA car. The compression # when hot are 320, 280, 350, 300, 300, 300. They are not brilliant but acceptable. The engine has 342K so it is tired and needs a complete overhaul eventually. This is what I did on and off over the last 2 months.

1) install/remove the head 3 times.
2) remove oil pan.
3) push all pistons out. Clean piston and groves. Honed cylinders slightly. Replace piston and oil rings if broken.
4) Replace oil pump chain and re-crimp.
4) Re-install pistons and head.
5) Do a leak down test and it shows each cylinder at about 10-15% which is within limit.

This is a kind of minimum amateur-ish engine overhaul. This is picture of the end product. It has high mileage so I would be very happy if it can do another 30-50K. I recharged with R134 and just discover all leaked out so there is a leak somewhere. What a PITA with old car but at least it is alive and running. Thanks for the help from various members.

winmutt · #45 02-15-2013, 09:35 PM

Quote:

Originally Posted by ah-kay

The car is back on the road now and has done 400 miles. No blow-by to speak of, idle smooth, no smoke. The engine seems to be a bit noisy but it could be my imagination. I managed to resurrect a nice rust-free CA car. The compression # when hot are 320, 280, 350, 300, 300, 300. They are not brilliant but acceptable. The engine has 342K so it is tired and needs a complete overhaul eventually. This is what I did on and off over the last 2 months.

1) install/remove the head 3 times.
2) remove oil pan.
3) push all pistons out. Clean piston and groves. Honed cylinders slightly. Replace piston and oil rings if broken.
4) Replace oil pump chain and re-crimp.
4) Re-install pistons and head.
5) Do a leak down test and it shows each cylinder at about 10-15% which is within limit.

This is a kind of minimum amateur-ish engine overhaul. This is picture of the end product. It has high mileage so I would be very happy if it can do another 30-50K. I recharged with R134 and just discover all leaked out so there is a leak somewhere. What a PITA with old car but at least it is alive and running. Thanks for the help from various members.

Tell me more. You must have removed the engine for 2-5 right? Seems like an engine swap is easier and probably costs the same.