Clattery 300CE - M104 Checking lifters (cam followers)

[bbarcher]

Hello,

I am working on my neighbor's 91 300CE again. It has the DOHC 24V M104 engine. Recently it developed a horrible sounding clatter. When she started it, the car had been sitting for not more than a day, it's a daily driver. When it started, loud upper engine noise was obvious. I made her turn it off quickly, so I don't know whether the noise lessened after the oil pressure pumped up the lifters.

I advised her not to drive it. Today I took the valve cover off and checked some of the lifters that were not being pressed down by the cam. Some of the lifters went down pretty easily and made a light clacking sound as they bottomed out. Others felt more resistant, but could still be pressed down all the way. All of the ones I checked returned back up after pressing. The engine has about 150,000 or more, not really sure but the car has not been carefully looked after. It has some rough edges but it was running good. I worked on it last summer to replace a leaking hose under the intake, and she was driving it daily since then.

I'm looking for advice from those that have been there. What should I replace, how far should I go? Do you think the lifters should all be replaced together? Kind of expensive, looks like 24 lifters x $20 each. I am also hesitant to go any further, since I don't want to open a can of worms. Better to let a shop do it for her? She is paranoid about getting ripped off.

I'm thinking about trying some different oil. She is careful to keep it changed, but I'm not sure what viscosity it has. I have had pretty good results with 15-40 Delo on my 190E. It had some noises that have lessened since I owned it, and it seemed affected by oil type.

Thanks for all your time, I greatly appreciate it. I have gleaned much knowledge here. I have done some searching, but not sure if I have found the right answers on this type of noise.

[Robert Squires]

* So it was fine one day (no noise) and then the next day all h@#! breaks loose? Hydraulic elements usually give more warning than that. They peck now and then for a while and then they peck continually. Have you taken a good look at the chain tension, specifically the condition of the tensioner and/or the stretch in the chain?

[Chas H]

Did you check the oil level?
Some other makes have chronic HLA noises and changing the oil seems to quiet them.

[bbarcher]

The history of the noise is a little uncertain, the owner has said she noticed it one morning, but she easily could have missed the smaller noises at first. I have worked on her cars before, and it always seems that her descriptions are way different than what I end up finding in the end... So I have avoided putting too much stock in her descriptions, I try to focus on the facts that the car presents. The last time she asked me about the car was about a month ago, the brake pad light was illuminating. She made no mention of anything else wrong. So it does seem fairly sudden. The first she noticed it was when she went to work on Saturday. I looked at it Saturday evening and it was sounding pretty bad. At the time I checked it, though, it was on an incline of about 25 degrees nose up. She had topped up the oil while on this incline, and I have not yet verified the oil level while the car is sitting flat.

I did not check the timing chain tension. I have to remove the front cover to check the tensioners, right? I would rather not do that. Part of me wants to put the valve cover back on, run some Seafoam in the oil to help dissolve deposits, and then change the oil and drive it hard to get the oil hot and let the detergents work. I like to avoid repairs due to deposit buildup since they can often be dealt with using chemicals. And I wonder if the lifters stick open due to dirty oil. The little check ball and passageways are quite small in the lifter. Perhaps someone could elaborate on this theory since I have little actual experience with these engines.

My situation is this: I am trying to decide which way to go with this. I have limited space (no garage to put the car in). What easy things can I do first? At what point do I stop and send it to the shop?

I will check the chain tension and try to determine how much it stretches. I am a little scared to start it and see if the noise changes as the oil pressure comes up, but I may try that too. I think it might pay to see if the oil change may help. I will let you know, and I thank you for helping.

[t walgamuth]

Those hydraulic adjusters are sensitive to correct oil usage. Using a 15w40 in my 84 500sec caused an adjuster to stick and tap until the engine was very warm. The dirty oil seems possible to me too. I would verify it has oil pressure then change the oil to a mobil 1 synthetic in the weight specified by the owner's manual and see what happens.

Tom W

[bbarcher]

I'm not sure how to check the chain tension, I looked at it and felt on it. I know there is a way to measure it using a dial gauge like on the 617 diesel, is that right? But I have no written instructions on what to check. Anybody care to elaborate?

For now, I reinstalled the valve cover. I haven't tried running it yet to see if the noise changes. I think that will be next.

[Ferdman]

bbarcher, I agree with changing the oil and using Mobil 1 15W50 ... that's what I run in our 1991 300CE. The timing chain tensioner is on the passenger side of the engine ... no need to remove the front cover to inspect/replace it, but you need to know what you're doing to reinstall it correctly. I'd recommend not touching it unless you have a service manual or service CD with step-by-step instructions.

[t walgamuth]

I don't think the tensioner has anything to do with your hydraulic adjusters. This seems to me to be totally oil or oil pressure related.

Tom W

[bobs]

Does the M104 have those little oil tubes like on the M119?

[bbarcher]

No little tubes that I saw with the valve cover off. The cam must be lubricated through hidden passages in the head? Noticed some carbon was filling the heads of some of the allen hex bolts, though. I have a copy of some instructions on the tensioner, and it says you have to remove the air pump. I am worried about having to replace the serpentine belt tensioner if I disturb it, as warned by the helpful Steve Brotherton article. So I am not too worried about the chain tension yet. Has there ever been problems that are limited to the chain tensioner and it's spring breaking? Or is the tensioner something you really needn't mess with until timing chain is replaced?

I picked up some Delvac Super 1300 15W-40 (for diesels, this was the last of the older kind that didn't say "low emissions" --extra detail for the oil people) to try. She mentioned upon further questioning that she had Firestone change the oil. So who knows. Also purchased some Seafoam but not sure about using it due to some skepticism online. Wouldn't it be safe to use as long as you don't heavily load the engine or rev it too much? If the oil is already in good shape, would using Seafoam in the oil be acceptable like it claims on the container?

[bbarcher]

Moved the car a little to get closer to my garage, and noticed no oil pressure showing on the gauge at all. When I asked her earlier, she said the gauges were not showing anything weird, and she usually is good about watching the oil pressure-- since it was broken when she acquired the car. I fixed the gauge last summer and it was working fine with the replacement of the sender.

I took the oil filter out and it looked like all the oil had drained for awhile in the canister housing. I don't think any oil is making it up. Poured a little Seafoam and some synthetic oil down the holes at the bottom of the filter housing, hoping that maybe it will free up a stuck oil pressure relief valve at the oil pump. I have read that these stick sometimes and dump the oil pressure. I'm guessing this is the problem. Difficult to repair since it requires removing the oil pan . Please pray that the M104 is not damaged.

[Ferdman]

bbarcher, I had the timing chain tensioner replaced on our 1991 300CE at 77k miles due to a muffled clatter at the front of the engine. A local independent felt it was OK-as-is, but after some prompting the MB dealer's Service Department discovered that the tensioner wasn't holding oil pressure properly causing excess slack in the chain. A new timing chain tensioner eliminated the noise. As for the oil draining from the oil filter canister, that's normal ... when the oil filter is removed a check valve opens to drain the canister.

[bbarcher]

Thanks for the info about the tensioner. That sounds like it was a relief to get fixed. This engine has no oil getting to the cams and lifters, that's why the noise is so bad. All the lifters bled down when the oil pressure was lost. The canister would have been wet from recently drained oil, but it looked like it had drained for several days, even right after running the engine. There was no oil dripping from the filter.

I don't know if it's toast, but it ran for awhile with no oil pressure. I advised her to tow it to a MB specialist before it starts knocking.

[arvy]

Had a loud clattering sound on my M103 that I thought to be a bad timing chain tensioner. The problem surfaced suddenly one day. Had the 300E towed to mechanic. Turned out to be a bad fan clutch. Indy replaced fan clutch, bearing bracket, and related parts. Problem solved.

Still replaced the chain tensioner for good measure / insurance.

[Ferdman]

bbarcher, sounds like the oil pump has failed if oil is not getting circulated throughout the engine. How did the camshaft lobes look? Hopefully your neighbor didn't run the engine too long with no oil pressure. I'll be interested to hear a professional diagnosis of the problem and the repair cost.