PeachParts Mercedes-Benz Forum - 617 turbo valve adjustment lobe position

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Err on the side of caution

While of course it's best to adjust valves in the correct way, it's always best to make sure the clearance is *at least* what the manufacturer specifies.

One of the most consistent errors made by DIYers is to adjust the vavles too tight.

If the valves are too tight, then very hot combustion gases are burning away at the valve sealing surfaces.

If the valves are a *little* loose, there might be a little more noise - but unless you go mad, it's unlikely to cause any significant problems with wear.

My experience of this is that I have corrected the valve clearances of a number of cars which have been "DIYed" with tight valves and have consequently failed the UK annual emissions test on high HC values.

If you set the valves slightly off the opposite of the cam lobe - somewhere on the quieting ramp of the cam - you will effectively make the valves a little loose. This is no bad thing in my opinion (although if you do this on a French car, you *will* hear the result!).

Quote:

Originally Posted by Number_Cruncher (Post 1676111)

One of the most consistent errors made by DIYers is to adjust the vavles too tight.

In order to find out if I adjusted my valves too tight I'll have to take off the camshaft cover and check next week. Your comment has me curious. I am new to MB diesels and I found it hard to tighten the two nuts without have the gap change. The factory manual states the feeler gauge should drag a little when you remove it. I found it easy to get a close loose adjustment than set a gap in which I felt friction with my gauge.

Quote:

Originally Posted by Number_Cruncher (Post 1676111)

If you set the valves slightly off the opposite of the cam lobe -.

When you say slightly off the opposite of the cam lobe, does this mean you would set the the gap with the cam lobe positioned at 1 o'clock or so on the drivers' side of the car?

Bob

Quote:

Originally Posted by Bob300DSD (Post 1676173)

I mis-spoke, I meant to say taking off the camshaft cover.

Note that you can edit your posts. Hit the http://www.peachparts.com/shopforum/...ttons/edit.gif button. You didn't have to quote and then correct yourself. ;)

Hello, just did an adjustment on mynew to me 82 300cd. I used the metal bar that stretches across all the cam towers as the reference point. That put me a bit beyond 1 o'clock but it looked right per the manual pictures.

Does anyone just align the lobe with the metal bar?

I havent done an adjustment since about 2003, and hope I didn't do it wrong. All were tight - I'll post the values later. I thought it was due to being due...

Thanks!

Quote:

Originally Posted by JHZR2 (Post 2355010)

Hello, just did an adjustment on my-new to me 82 300cd. I used the metal bar that stretches across all the cam towers as the reference point. That put me a bit beyond 1 o'clock but it looked right per the manual pictures.

Does anyone just align the lobe with the metal bar?

I haven't done an adjustment since about 2003, and hope I didn't do it wrong. All were tight - I'll post the values later. I thought it was due to being due...

Thanks!

I use the cam shaft oiler tube as reference point.. :D

Everything you need to do it correctly is here..

Valve adjustment OM617 FYI.
http://www.peachparts.com/shopforum/diesel-discussion/107729-valve-adjustment-om615-616-617-fyi.html

Have a great day.

Thanks.

So you line up (or point) the "tip" of the cam lobe with that tube?

My main concern is because before adjusting, I had the following readings:

#1E: .203mm
#1I: .152mm
#2I: .127mm
#2E: .229mm
#3E: .254mm
#3I: .173mm
#4I: .179mm
#4E: .229mm
#5E: .229mm
#5I: .102mm

So I had set each cam lobe to point exactly to the oiler tube on the cam towers. It matches up to the instruction pictures that way IMO, and also the cam is round for 120 degrees or so, Id guess there shouldn't be much variability, but those were pretty far off from the .10mm in and .35mm out per the sticker on the car. The interesting thing to me is, if they were done "right" last time, then while the exhausts all got tighter (expected), the intakes all got looser, how is that? The other option is that the last time the wrong specs were used.

Car idled and ran perfectly with those old settings. Going cross-country, I got mid 28 MPG, averaging 75 MPH, and spending time above or near 7500 ft.

One other thought/question. I did this job roughly at freezing. The car was definitely cold soaked, having not been used for over a week. Could this be "too cold", and cause me issues again later when ambient gets warmer?

Chain stretch at TDC: 4 degrees

http://i83.photobucket.com/albums/j3...D/IMG_2015.jpg

As clear as the FSM states where the cam lobe is supposed to point I can not believe there could be this much discussion about it.

If a person is having trouble getting and keeping the proper tolerance during valve setting the FSM suggests putting new cap and lock nuts on the valves as a first and cheap possible fix for the situation. They take a lot of pressure and pounding...so they can get worn on the threads and make it hard to hold the correct distance through the tightening process.

As clear as the image is in the manual and in haynes type manuals, Im suprised that it is not mentioned that the oiling tube can be used as a reference point. It sure seems to line up right for me. But for those of us who have never really had to do this job before, and see it as a task with much to loose beause of a general lack of full understanding... it is important to have a sense of correctness and surety to the process.

Still, it helps to have a sounding board to ensure that my thought process and technique is absolutely correct, or not. Sure seem to see conflicting stuff, from vertical to one o'clock... Im referencing the graphic for angle and design of the system.

One thing that I did not do was crank all around and then recheck. Hope they are OK. The nuts all worked fine. Some needed a bit of oomph to loosen, but they worked, loosened and tightened just fine.

Bob,
I was originally trained to use 'go - no go' That is the nearest thickness combination that you have that is less than the required gap should just slip through and the nearest thickness combination that you have that is greater than the required gap should only go in with some force. Its worked for me for over 30 years. I dont get excited about +/- a few degrees on the position of the lobe, I cant measure a difference. I once moved the cam from just past 11 oclock to just passed 1 oclock , the difference was hardly measurable , the difference was much less than comparing a cold motor with one in freezing conditions!
My 84 300d, was a bargain, it was mid winter and the dealer could not get it to start. It had new glow plugs & battery. I was told I would need to take it on a trailer. I bought it, then borrowed 2 open enders and a shifter off his mech, and adjusted all the tappets so they had some gap, 4 of them had none, didnt even use a feeler gauge. Put it back together & it started right up. You should have seen the dealer & mech's faces -- Priceless!! I adjusted the gaps properly about 200miles later. I have found its better to check the gaps regularly, say every 40,000miles than to get concerned about the last half a thou.

Quote:

Originally Posted by layback40 (Post 2355266)

I have found its better to check the gaps regularly, say every 40,000miles than to get concerned about the last half a thou.

That doesn't sound too regular to me. I thought the recommended interval was 15 KMiles? I do mine with every oil change at about 10 KMiles.

Quote:

Originally Posted by micalk (Post 2355287)

That doesn't sound too regular to me. I thought the recommended interval was 15 KMiles? .

LOL, That is exactly what I thought when I read that....

Quote:

Originally Posted by layback40 (Post 2355266)

Bob,
I was originally trained to use 'go - no go' That is the nearest thickness combination that you have that is less than the required gap should just slip through and the nearest thickness combination that you have that is greater than the required gap should only go in with some force. Its worked for me for over 30 years. I don't get excited about +/- a few degrees on the position of the lobe, I cant measure a difference. I once moved the cam from just past 11 O'Clock to just passed 1 O'Clock , the difference was hardly measurable , the difference was much less than comparing a cold motor with one in freezing conditions!
My 84 300D, was a bargain, it was mid winter and the dealer could not get it to start. It had new glow plugs & battery. I was told I would need to take it on a trailer. I bought it, then borrowed 2 open enders and a shifter off his mech, and adjusted all the tappets so they had some gap, 4 of them had none, didn't even use a feeler gauge. Put it back together & it started right up. You should have seen the dealer & mech's faces -- Priceless!! I adjusted the gaps properly about 200 Miles later. I have found its better to check the gaps regularly, say every 40,000 miles than to get concerned about the last half a thou.

Congratulations on getting the car cheap.

Note: if everything else is OK, your method will get it running.
The correct method gives better results.
You do not mention how long it takes you to run up 40K miles.

My valves are adjusted every fourteen months.
This is a convenient service interval for me.

If a person has trouble getting and keeping the proper tolerance during valve setting and/or looses adjustment quickly between service intervals the FSM suggests putting new cap and lock nuts on the valves as a first and cheap possible fix for the situation.
They take a lot of pressure/pounding, and become worn on the threads making difficult/impossible to hold the correct setting.

Call Phil for these parts
1-888-333-4642

Top nut (two per engine cylinder)
MB# 615 053 00 72

middle nut (two per engine cylinder)
MB# 153 990 02 51

As stated..

I use the cam shaft oiler tube as reference point.. :D

Everything you need to do the valve adjustment correctly is here..

Valve adjustment OM617 FYI.
http://www.peachparts.com/shopforum/showthread.php?t=107729

Quote:

Originally Posted by whunter (Post 2355060)

I use the cam shaft oiler tube as reference point.. :D

Everything you need to do it correctly is here..

Valve adjustment OM617 FYI.
http://www.peachparts.com/shopforum/showthread.php?t=107729

Have a great day.

I oriented off cam oiler tube as well -made eye balling a lot less complicated!