Ok I have a 603 engine that I picked up some time ago and went through every bit of it. My issue is with the machine shop who I had skim it, install new exhaust guides and re cut the valves. With the head installed she smokes white, did a compression test all sitting around 400 psi no. 1 being the lowest 350. Leak down shows significant losses past the valves. I removed the head and returned it the vacuum test indicates it holds at 20 inches.

Its a small shop but they are unwilling to understand vacuum testing and insist since they hold 20 psi, (I dont know how to argue with stupid) everything is fine. I then lapped the valves but same issue leakage past valves and now I'm beginning to think maybe the head isn't flat. They tell me just to run it but after several hours of running it with no load no change.

Not really sure what to do now but not to keen to return again. So she has been sitting. Is it normal to have to run the engine presumably under load to actually seat the valves?

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92 e300d2.5t
01 e320
05 cdi
85 chev c10

What cyl head casting number do you have?

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18

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92 e300d2.5t
01 e320
05 cdi
85 chev c10

Try measuring the flatness of the head with a straightedge and feeler gauges. I ended up not skimming my #17 head because I wasn't able to remove the pre Chambers but measured with a straightedge the head was flat. White smoke is usually water intrusion into the combustion chamber. Is it consuming coolant?

You can test the seal on the valve seats easily enough with the cylinder head on its side on the workbench by pouring water into the port and holding the valve shut. I kept lapping my valves until no water leaked out. After the rebuild I have ~400 PSI compression across the board. Prior to lapping the valves were badly pitted.

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I havent run it more than 4 hours since its not in a vechile. I suspect it maybe consuming a small amount of coolant as I'm outta ideas and did notice a pressure release when I removed the expansion tank cap. I have not been able to see any air bubbles in the coolant when running. A leak down dosen't tell me anything more than all valve leak except 1.

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92 e300d2.5t
01 e320
05 cdi
85 chev c10

Perhaps since you are testing on a closed cooling system. Try bringing it up to operational temperature. Let it sit and cool overnight. If system is still under substantial pressure then. Verifies the cooling leak or not usually on these engines.

As you mentioned nothing is conclusive. Yet this test might help figure our what is happening. Also a mirror or piece of glass held in the exhaust stream. If condensation occurs on the surface it is coolant. Coolant will have nothing to do with the valves.

If instead it is non condensing un burnt fuel. Then it could get interesting.

Actually I am getting a little lost here. Or missing something. You have very good compression yet you think the valves are leaking heavily. Perhaps just introducing an air pressure into each cylinder in turn. Listening for leakage at the appropriate places and watching for bubbles in the cooling system. No detectable leakage noise from the intake or exhaust. You have to assume they are usable.

The 603s when they start are normally smooth enough. As far as I am aware. Their combustion is aided by the glow plugs. As the glow plugs shut or cool down. Does this engine roughen up until it warms up? If not it has to be functioning reasonable well. What I describe seems to be a characteristic of these engines.

Anyways my first effort would be to look into the white smoking first. I am aware in a way it could be created by a valve situation. At the same time if the coolant is the white smoke. there is no way it is. Then again these are just my opinions. You probably just have water in the system as coolant presently. If you just are not positive of what the smoke is. Putting anti freeze in the system should produce a sweet exhaust smell when being used.

All I know is perhaps I was lucky when I got involved with valve jobs. When I picked up the head or heads from the shop. I used a thin fluid to test for tightness of seal. If after hours they was no evidence of any seat leakage. The head or heads where put back on the engine. Just lucky perhaps but never seemed to have an after issue.

I kind of am back mentally where I started. I see the white smoke as one issue to look at first. As for the shop that did the valve job. Can you check on their general reputation? Where they busy when you took in and picked up the head?

If they check out. If they checked for sealing after the job. That is part of their job anyways. Chances are those valves are okay.
As speculation if the engine was not producing the white smoke would you have put it back in? My guess is probably yes. Since I have many limitations personally. I always go for the more obvious issue first.

First if say you gave the engine to me. I would want to know exactly what that white smoke is. Totally ignoring the valves until I found out.

Moving into deeper water. If you had good valves and white smoke. The engine is not ready for service anyways.

We did have some really bad automotive machine shops locally. As a general rule they had little work coming in and eventually failed. Valve jobs are a large component of their type of business. The only other thing I can think of is.

When you did your leak down test you where sure both valves where closed for each cylinder. I know that sounds stupid. At the same time I cannot visualize a lot of valve leakage with those compression numbers.

On the other hand I am neither a working mechanic nor have I done hundreds of valve jobs in my life. Last but not least was the white smoke the reason that drove you to do a compression and leak down test. After the head was done? I can see that. Would you have also done the leak down test if the white smoke was not present? After a compression check.

This was a long post. My point is we all from time to time get into fixed mindsets. As soon as I find I am in one. I walk away from the job or issue for awhile to regain hopefully a more reasonable perspective. I have to assume this does not work for everybody.

I just found in my case it was better than loading up on frustration. . It sounds like you had reached that point. Yet even after a rest it is still there. I consider this human in nature as well. I spent many, many years of my working life troubleshooting as a job. But it was on electronics. Some of the same issues and lessons learnt present themselves as very usable on all sorts of other issues.

You also have to find the brighter side of a problem of this type. In your case it is not an intermittent problem. Some of those can really work you over. Try to forget the valves for now would be a start. Does not really matter at this point what condition they are in. Until it is established the white smoke is positively not coolant. Still all in all these are just my opinions.

As mentioned white smoke can be coolant and if you hold some cardboard right at the exhaust pipe and smell it it should smell like coolant. If you do the same thing and it smells like fuel you could be having late fuel injection pump timing and or valve timing.

In that case the white smoke is atomized unburned fuel.

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84 300D, 82 Volvo 244Gl Diesel

He may just have water in his cooling system. In an external testing setup. He has to get this right. What actually is coming out as white smoke. As a certainty.

Your tests may be enough for him. May not. If there is not absolute certainty use anti freeze as the coolant. Produces kind of a sweet smell.

Or if it blows white smoke as soon as it is started. Drain the coolant system Start it up and let it idle for about 30 seconds.

Give the engine a rest and repeat this same procedure a few times. If there was any coolant in there remaining. It should be gone. Still smoking white on startup and continuing. It would be fuel. Short run periods of say thirty seconds each with reasonable intervals to cool between them will not hurt anything. Have to be sure of the identification of the smoke beyond any doubt.. May be very easy or a little harder but certainly doable.

I'm considering all possibilities currently. When I returned the head they did a water test and of course no leakage in 5 minutes. I'll find time tomorrow to shoot a video but with 10 psi and a bit of oil on top of the valves they just bubble away and I measure 30% plus leak down. That was with the cam removed!

Exhaust smells of diesel sort of. I did follow the manual with the head off to setup TDC. I have verified injection pump timing and advanced the pump to 7 degrees ATDC no change. Turning on glow plugs with engine running really changes nothing. I had cleaned and rebalanced the injectors but before removing the head again I need all data from tests fairly soon. I do have another set of injectors I'll check and install them. I will drain the G05 and try running it as suggested but will also try using a clear over flow pipe in hopes of seeing some bubbles in the coolant. I do see faint off gassing when I have the reservoir cap removed. I also put 10 psi on the cooling system when cold but loose that pressure after 10 minutes or so with no visible signs of leakage. I did check torque on the head bolts 3 were 70 ft lbs rest were 95 so I had replaced those 3 after recleaning the bolt holes did the 90 degs wait 10 minutes then 90 again and also verified the were 95 ft lbs. Figured I had nothing to loose at that point. Little maybe less smoking.

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92 e300d2.5t
01 e320
05 cdi
85 chev c10

Just to verify the leak down test you did was valid. At thirty percent leakage you would have heard the air escaping. Where was it coming from? Oil fill hole. Exhaust, intake? That is a fair amount of loss. Actually fairly heavy. You did the test at about 100 psi?

I think these heads experience seat depression with wear perhaps a little more than on average. There are limits to the amount on total loss of seat material allowed. A combination of previous wear and further removal of material can exceed the amount allowed. Regrinding the valve also increases the end of the valve stem length into the head as well.

If during your leak down testing you were hearing the air escape through the exhaust valves especially. I would put the flatter area of a can lobe on an exhaust valve . Apply pressure to the lifter to see if I can be further bled down.

There will be a spec on how much the valve stem is allowed to be elevated above the pocket bottom or some way to make sure they are not higher than they should be. All cylinders about the same percentage leak down. I still do not think if the valves seats held water for five minutes the physical contact areas between the seats and the valves are the issue. Now if they lied to you about that test is another thing.

For that much loss in the leak down test. With everything together though and too much material missing from the seats the valves may not be able to seat well. Again there will be a spec on what is allowed and how to check it. There may very well be dynamics where if that wear is exceeded. The lifter will not work normally. The only test that really counts would be by the measurement Mercedes quotes. As the upper level of how much material loss is allowed. It almost has to be the protusion of the valve stem above the lifter pocket bottom. This is just one possibility.

This could generate white smoking as raw fuel would escape into the exhaust system. This is just one possibility. Do not jump at anything. Think about it first and approach it properly. Since you have anti freeze in the cooling loop and the white smoke did not have a sweet smell. I think it is unburnt fuel as well.

Mercedes allows re use of the stretch head bolts. Only if their specified length measurement has not been exceeded. Some manufacturers do not. Years ago when I was given a choice on certain engines. If the head bolts were cheap I usually threw in a new set. If expensive at the time and reuse was allowed you know what I did.

Remember I am not a working mechanic. Yes they could have messed up the valve job. Just not quite the way you thought. It might have needed new seats to restore the proper relationship with the rest of the valve train. Again at this point it remains but one possibility until proven.

Other members with more experience could chime into your post. My knowledge is far below many of their levels. If you did hear the air escaping into the exhaust heavily. During the leak down tests. Either your thought of a very poor seal exists valve to seat. Or the same effect is occurring because the valve pockets may be too deep.

I believe other members could verify that your models head has a history of deep valve pocket wear in service. Usually in the rear cylinders. With those requiring new valve seats. If the valve head itself was machined in production. A measurement of the head of the valve to the surface of the head, Perhaps would be another way to tell is the valve pocket was too deep. At least on initial inspection when a head was pulled. Because of production variences I suspect their measurement requirement will be at the stem end.

Of course cam timing can also produce the leak down effect you experienced. You just cannot be more than one tooth off without damaging valves.

One last thing I do not think your problem is but I have to include it. Your engine will run not too bad with the injection pump on the wrong stroke. The earlier engines will not. One member drove his car after purchase a long way home with that issue.

You would not have the normal clues that presents as your engine is running outside the car. But you do have the white smoke. If you are absolutely sure before you pulled the head the cam marks and balancer marks where set. Then there is no reason to verify the blade in the injection pumps window is present at the right balancer marks required when that cam mark is where it should be. If you pulled the head without aligning the marks first you might want to have a look. In a way just to verify a stack of problems do not exist. Most issues land up getting resolved with help on site. Usually something is missed when they do not.

I am trying to think but have a heavy workload that is interfering with the process. Things like the engine having basically the same amount of leak down across all the cylinders. I cannot seem to get mentally resolved. Normally I would expect the cam was off one tooth. With a little existing chain stretch perhaps adding to it. It is almost like the valves are slightly open when they should not be.

https://www.google.com/url?sa=t&source=web&rct=j&url=https://m.youtube.com/watch%3Fv%3DFjgwWt-ZdxI&ved=2ahUKEwiY98W4vKTeAhUiIDQIHakABU0QjjgwAHoECAYQAQ&usg=AOvVaw3_W4kQT2Y52aw1eQInqdmo

The quality is not great on this video but I was a little surprised to see the amount of bubbling had decreased. My former leak down test was at 50 psi and I had both manifolds and cam removed and could hear and see the bubbling. one would think compression would be lower if the valve was not seating. At about 2500 rpm the smoking seems to disappear below that a definate diesel smell similar to a compromised head gasket.

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92 e300d2.5t
01 e320
05 cdi
85 chev c10

Well since the leak down test was preformed with the cam off. At least there are certain possibilities removed. No you should have not heard the leak down test through the valves of a fresh valve job.

A very small amount of leakage perhaps might exist. Enough to have heard it out of where you are shining your light does not sound reasonable. The leak down test loss was pretty substantial. Unless the bulk of it was going down the bores.

How it passes the water test and does not yours. I do not think molecular size answers that question. Although from past experience I know the water molecule is large.

The engine would run better at higher rpms because the time constant for loss of volume past the valve is reduced. Same basic thing with the compression test.

I am now having a hard time with this. Things like a fresh valve job breaking in? Does what you and I can see but can hold water? Leak down test where you can actually hear the loss through the valves right after a valve job. Plus the high rate of the leak down.

I have limits but I would speak to another auto machine shop . Make sure they are credible first. Usually any local mechanic can suggest one they use that they are satisfied with.

They may even have a word to say about who you used. At this time that is important. If your leak down test at 100 pounds was say five percent. I would not consider this an issue. Thirty percent at 50 pounds is another whole story.

If you had done the leak down test at the usual 100 pounds pressure. The result would have been even worse. Can you imagine just how the bubbles would be frothing . You are only at a low relative pressure in the video.

I hate to say this but there may be some real issue with that guy. That did the valve work. I once ran across a shop where they where so high they should not be working on cars when I was there. People only went to the front desk. I go first to the back shop when I can first. That has served me well on those infrequent times I have used paid for service. If it is pretty much empty there is a reason. Good fair places are usually backed up with work. Even in this economy.

Your thread is interesting enough. I would like to know how things go. Others would as well I imagine. For what it is worth. Part of the incoming fuel charge may be getting past really leaky exhaust valves creating the white smoke.

When I was looking for a machine shop of which there are 7 who work on heads I first had a list of questions I talked over with the lead which immediately discounted 4 shops. Of the 3 remaining the shops I then visited to see first hand what was going on in the shops. I selected this 2 man shop the lead in his late 50's took over from his father and now has his son in training. I don't believe he is too educated but with that much experience and the volume of work they had lined up was impressive. I don't think they are dishonest but rather are not prepared to go outside the box so to speak. The first time when I ran the engine and saw the amount of smoke then started diagnostics the my eyes popped when I saw this bubbling. Then off cam the exhaust manifold still this bubbling then off came the cam and my eyes were still popped. So I took it back and they kept it for 3 weeks promising to remedy the issue but could not replicate it. I tried telling them the vacuum tester they were using had too much volume so of course it would suck and look like they were seating. After talking to another shop if it passed the vacuum test it is a good and complete job so now its up to me to figure out what's what.

I like your theory on valve length displacement increasing due to cut seats and valves so I looked up valve lengths original 106.4 repair valves 105.5. I'm wondering if the lifters pump up too much with a running engine but then bleed down fast enough that I can't observe what is actually happening. I suppose I could remove the lifters and squeeze them to a fully compressed state then give it a shot. The lifters I'm using are the original used lifters.

I would need to pull the head to measure valve seat distance in relation to the head which can be as much as -1mm but I recall seeing them flush or slightly proud.

The smell when running is definitely diesel. So I guess if somehow the IP is off with the tang I could verify using the drip method but will need some help with that. With the valve cover removed I did check all the alignments and cam position so cam timing is dead on and new oil and cam chains I had installed.

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92 e300d2.5t
01 e320
05 cdi
85 chev c10

I do recall reading some other member or members experienced smoking after a valve job but never indicated for how long. When I had run the engine for 4 hours and since the engine is freely mounted I really have no way to load the engine. Believing it would just take some run time my attempt to hammer in the valves to seat I sprayed from a distance a light amount of starting fluid which immediately changed the exhaust to a nice black. Maybe I'm impatient and the thing just needs to run and run?

I just found a reference to document 05-211 checking hydraulic lifters in relation to machined seats. Anyone have access to the 124 om603 maunal and can supply a copy please my wis is currently in need of a painful reinstallation.

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92 e300d2.5t
01 e320
05 cdi
85 chev c10

Mine didn't smoke at all. Before and after lapping.
https://imgur.com/SLzwFOg

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