New Camshaft?

[Pawel66]

Modified the post a bit...

I guess I am in need of looking for help in answering a couple of questions. I have been complaining on a fairly noisy running of my engine on the top. I started looking at things under valve cover closely (this is not about a simple valve adjustment - this I did, and it did not help).

The engine runs vey nice and quiet when warming up. Once warmed up, it starts being noisy. What I found:

1. Camshaft. I do not see dark wear spots on the lobes. But the cams height varies up to 0.3-0.4mm (intake and exhaust cams have overall different height, the diferences are, however, between the inlet cams within the inlet cams group and same for exhaust cams). Is this acceptable? I would not think so if we have e.g. 0.08mm clearance precise value. On top of that I have pits on two lobes. Not a lot, but a 3 to 4 spots on each, up to 1mm diameter. It is on the working parts, where the cams press on rockers.
Is my shaft to be replaced?

2. How do I determine (part of the history is lost) if I need 4.5mm thrust washers or 3.5mm? I am pretty sure the valve nests were ground, but I do not know how much. I saw on the forum that there is information on this in BBB (length of valve vs. thickness of the thrust washer), but I could not spot it in the BBB.

3. As part of the history of engine rebuilt is missing - is there a place where I can measure the head while it is installed on the engine? That would allow me to check how much I have vs. 85mm. But this measurement when the head is installed may be tricky, that is why I am asking if it is possible and how.

Please chime in if you can help.

[Pawel66]

I have modified the post a bit, hoping it is clearer now and with fewer spelling mistakes...

[Benz Dr.]

I believe that the intake and exhaust cam lobes are not the same size so I wouldn't get too excited about that. Cam shafts can be reground and be every bit as good as new. I would use a .015'' cam bearing shim under each bearing if you change the cam profile by grinding.
They should be able to grind material from the base circle of the cam which will help to retain cam lobe lift so that a smaller amount is removed from the lobe. Pitting on the lobes could be caused from using oils that are not high enough in zinc. I use a 15 W 40 oil commonly used in diesels so obtain enough anti wear additives.

[Pawel66]

Dan, thank you for advise on this.

The 0.3 - 0.4mm differences are between intake cams and there are similar differences between exhaust cams. I mean: intake cam 1 would have, say, 40.2mm, intake cam 2 would have 40.5mm, intake cam 3 would have 40.6mm, cam 4 would be 4.3mm and so on (I do not have the notes on me). That is what seemed quite a lot to me... yes, there was a difference on average between intake and exhaust cams - but I figured that is ok. But the difference between the cams of the same type seemed to be an issue.

I am not sure if I understand using the shims - if I grind cams, I increase the distance lobe - rocker. That to me probably indicates using the nominal thrust washer (4.5mm) and screwing out adjustment pin. If I raise the camshaft with a shim - I would increase the distance even more as the camshaft will go up... sorry - I have limited experience here. I was reading all your posts about the shims while doing my homework before posting the topic and I thought you use shims to compensate for ground valve seats (I wrote "valve nests" before, sorry, this was direct translation from my language) as the valve goes up after grinding.

I understand the point about grinding around the cam, thank you.

I wonder how much you can grind before you get to the end of the hardened material layer...?

Having studied the forum, I do use 15W40 mineral after engine repair, I was planning on switching now to synthetic 15W40. No idea what POs were using...

Just thinking - if I go for grinding as you say, I may as well go for a new camshaft - we have a camshaft guru here, who does all the racing teams and also he did the camshafts for half of Mecedes Benz club here... Price is ca $300. Maybe it is better option than struggling with the pits, etc. Not sure...

[Benz Dr.]

All good questions and you might have a point about grinding the cam. Grinding the cam can make the base circle smaller, which I guess when I think about it, would require that you raise the rocker arm to compensate for that removed material. In the case of grinding the valves or seats, or removing material from either side of the cylinder head, the distance between the rocker and the the valve stem ( thrust piece ) would be smaller. In order to bring rocker arm geometry back into specs the easiest way is with cam bearing shims.

Since valve lash is set using the base circle on the cam, and the base circle has been reduced in size, I think it's safe to assume you would need to raise the ball stud to adjust to this new setting. This  applies more to cam grinding and not to any or all of the other processes that may be involved in rebuilding a cylinder head.

[Pawel66]

Ok, I understand, thank you.

Funny thing is: when I spoke on the phone with this camshaft guru, I started desxcribing the issue (pits, different cam diameters), before I got to the point on the noise when the engine warms up, he broke in and said: "oh, then you must be getting noises whne the engine warms up!"

The more I think about it, the more I am inclined to get a new shaft, actually. What I need to check is the camshaft surfaces that are inthe bearings...

[cfm65@me.com]

Hi Pawel,
I dont know if it was mentioned before. Seriously consider a new timing chain as well as a new chain tentioner.
Regards
Chris

[Pawel66]

Chris, thank you for a tip. Both of them are new. Personally bought them in MB when the engine was put together. I wil check how they work and look.

[Tyler S]

I helped out a fellow member with this exact problem a few years back. His camshaft had been ground, the head surfaced (top and bottom) and the valve seats ground. This thing was noisy!!  The rockers were making contact with the valve spring cups. We ended up shimming the cam bearing towers, replacing the camshaft, and installing 3.5mm thrust caps (this compensated for the ground valve seats).

[Pawel66]

Tyler, thank you! I am paying attention exactly to what you are saying. I have read the posts on tis topic, including yours. I am very aware of the rockers hitting the cups and I check it each time I do something with valves. Although this applies probably more to the old type rockers that were replaced, when you do not know exactly how much material was ground on head and vlave seats - I thought I had better be careful.

I donot yet know what I have under vlave cover (which camshaft type), but having read the posts I would definitely like to end up with 02 (late engine, euro car). If I have 02 - we may re-grind it. If not I will either re-create it or buy a new one.

Then I am not sure if I should use 4.5mm thrust washers or 3.5mm. I am pretty sure my seats were ground, not sure how much.

Last question is: shall I replace the rockers? A lot of people say I should not to damage the new camshaft. My rockers are fairly good looking, so I was thinking maybe a bit of grinding would smooth them - I am not sure however, if this is an acceptable practice.

[Tyler S]

You may have mixed results in trying to refurbish the rockers. I ended up replacing all of mine when I replaced my camshaft. I did not want to risk damaging a $700 camshaft. Not to mention the rockers mating material is hardened and you will loose that if they are ground. I put the cheaper Febi ones in and have had no problems. You may not need the 3.5 mm caps if the cam bearings are shimmed and cam is ground.
In response to your other question, you can measure total head thickness on the car just behind the IP. There is just enough of a lip on the bottom of the head to do this. But this will only tell you total thickness, not how much of top or bottom was removed.

[Pawel66]

Tyler, thank you again for your valuable input!

As for the rockers - I will look for them then. The price in MB threw me out of my socks. Then I saw prices in Niemoller and SLS in the range of EUR 30-35, much better. If I can find similar price from branded manufacturer - great. Just found Febi - EUR 20 per piece  .

Thrust washers: I already have 3.5mm. The 4.5mm are, as I understand from EPC, no longer available. 4 of the nominal ones I had on the car someone remade incorrectly, so I would have to make them again. I will see how it all fits. I just modified my post - the 4.5mm are available, actually... I can buy 4 to have the 4.5mm set if need be.

Thank you for the tip on the head thickness. I know I will not know everything, but at least I will have some idea how far or how close I am from the minimum of 84mm.

[Tyler S]

Yes, the 85mm total thickness when new. Subtract your head measurment from this and it will give you a rough idea of how thick your cam bearing tower shims need to be. This will bring the camshaft to the proper height in relation to the block (this is for correct cam chain timing as well as clearances).
This will also help with rocker geometry.
This is the repair to do first before determining if you do indeed need different thrust caps.
BTW have you double checked the cam chain tensioner to make sure its bleed properly and the tensioner arm isnt bottomed out? Could be part of the noise issue

[Pawel66]

On the shims and distances - ok, understamd, will follow this.

How do I then determine what thickness of thrust washers I need? I can think of removing head and do some complicated measurements, but I would prefer to avoid it...

No, I have not yet double checked the tensioner. Honestly, I have a very vague idea on how to do it properly (have not done my homework on this yet). I may only guess that chain tension is one of the checkpoints. I have read somewhere that you need to press on the tensioner and it should give way just a little bit under considerable force (BBB?). But I do not know how tensioner arm bottomed out may look like...

[Pawel66]

Ok, I found Chain Tensioner Tour with subsequent posts. More educated now.

Thank you for pointing this topic to me.

[Tyler S]

After your cam brg shims are installed, the rocker adjustment ball studs should be roughly half way up their travel (threaded area) and the rockers roughly parallel to the head when valve closed/not riding on cam lobe. If your adjusters are bottomed out or close to it then you need thinner lash caps. Thicker lash caps if the adjusters are riding high etc...

[Pawel66]

Ok, thank you, I think I get that. So the rockers should be in essence in parallel to head while on the "thinner side" of the cam and adjusters not at extreme up/down positions. I have now ca 2 threads on adjusters above head level, but not sure how close to parallel to head rockers are.

Wonder where I would order the shims.... anyway - very halpful again! Thank you!

[Tyler S]

Having only 2 threads showing is definately tight. But the good thing is cam shims will most likely be enough to correct this as the adjusters are not bottomed out completely.
Over here in the States we get the shims from Metric Motors. However they most likely can be fabricated. Metric motors has different thicknesses that can be stacked to get your desired thickness.

[Pawel66]

Well, this is after moving them up for 3.5mm thrust washers...

I am sure I will find someone to make those shims.

[Pawel66]

Short update on my camshaft adventure, maybe helpful for the future for others.

Looks like our guru, Mr. Swiątek, www.swiatek.com.pl, has the specs and can produce camshaft based on Mercedes part number. It is about $300-350. He can also check and fit the bearings. He can also make shims for the bearings pedestals. He can also make thrust washers if need be (bloody expensive in MB when you make the price x12).

He is my guy.

I have not done anything with him before, but a lot of people I know did and they said he was ok. Particular achievement: he recreated camshaft for very rare 300SC from 1955 or so, as the original was broken in more or less half and he also guided mechanics on what the cause was for the failure so that they could fix it not to lose another shaft.

[Pawel66]

Further update: our guru did not do my camshaft as one of his industrial customers doubled their order and I was informed that, very sorry, but we cannot re-set the machinery until late January.

I had 02 camshaft in my car and I ended up buying the cmashaft from Mercedes. The guru just checked the bearings fit with the new camshaft.

I had the 0.4mm shims done for bearing pedestals. New camshaft, new chain, new tappets installed. I changed the oil to VR1 (one of the few alternatives available here with some 1400PPM ZDDP content).

The engine is much more quiet now or it may be a wishful thinking. I have not yet run it in as I am somehow scared to keep it at 2000rpm for 20 minutes....

By the way: when the guru saw my MB camshaft, he said: "Chinese job." I do not know if he wanted to underline his potential superiority or it is true.

[Tyler S]

Thats great. Be sure to break it in before you call it fixed. You will want to go back in and re-adjust the valves after 500 miles or so.

[Pawel66]

Thank you!

This breaking it in scares me. Cannot imagine car in a garage standing at 2000rpm for 20 minutes and driving is out of the question at this time of the year...

Yes, valve adjustment and, probably, head re-torqueing between 500 and 1000 km.