'89 107 fears, woes & questions

[rjk]

I don't think the kids maintained the 560 very diligently.

It looks like it ran low on oil sometime in the past year or so and it started clicking, then rapping so I had it towed to the house (smart move) and started looking it over.

Pulled the valve covers and both cams and all 16 rockers are toast (one rocker was broken in half, hence the rapping). All are scored on the mating surfaces.

Looked at the timing chain and it shows NO stretch (Both cam timing marks are dead-on). BUT one of the rails (upper, inner , drv side) is broken and stuck between the chain runs so I figure I'm in for a long weekend pulling off the timing cover (already done and only took part of Saturday).
Here are my questions of which I think I already know the answers but am hoping maybe I am wrong.

1) Is it normal for a 150K mi engine to need a 1/2" drive impact wrench to loosen the upper (nearest the intake mani) cam tower bolts? They should only be torqued to 50 nm from what I can see. As I loosened them, I feared I was going to strip the bolt head. When they finally came out, galling was apparent on the threads. It looks like they were installed dry. The longer bolts holding on the towers loosened up as I would have normally expected.

2) Some of the towers show a little scoring on the top where the oil enters, replace?

3) Haven't looked at the lifters yet, are they likely compromised?

4) Speaking of the long tower bolts, about half of them came out of their holes milky in appearance. Please tell me these bolts pass through the water jacket and that is why they are contaminated and I do not have blown head gaskets.

5) Since I have it opened up, should I replace the oil pump? Maybe the oiling problem started there and it isn't the kids' fault.

6) What about the water pump? Renew it as well? 150K mi on both pumps. By the way, the lowest bolt for the water pump sheared off, seems well and truly stuck and I probably need to drill it out. Any sage ideas?

7) With new cams & rockers I assume there is a calibration procedure to follow setting them up. Difficult?

8) Anyone have an A/C compressor for the beast?

I suspect the engine was opened up previously because of a few things I saw that didn't look like factory work.

Thanks all...

[rjk]

bump

anybody?

[Frank Reiner]

Originally Posted by rjk

I don't think the kids maintained the 560 very diligently.

It looks like it ran low on oil sometime in the past year or so and it started clicking, then rapping so I had it towed to the house (smart move) and started looking it over.

Pulled the valve covers and both cams and all 16 rockers are toast (one rocker was broken in half, hence the rapping). All are scored on the mating surfaces.

Looked at the timing chain and it shows NO stretch (Both cam timing marks are dead-on). BUT one of the rails (upper, inner , drv side) is broken and stuck between the chain runs so I figure I'm in for a long weekend pulling off the timing cover (already done and only took part of Saturday).
Here are my questions of which I think I already know the answers but am hoping maybe I am wrong.

1) Is it normal for a 150K mi engine to need a 1/2" drive impact wrench to loosen the upper (nearest the intake mani) cam tower bolts? They should only be torqued to 50 nm from what I can see. As I loosened them, I feared I was going to strip the bolt head. When they finally came out, galling was apparent on the threads. It looks like they were installed dry. The longer bolts holding on the towers loosened up as I would have normally expected.

2) Some of the towers show a little scoring on the top where the oil enters, replace?

3) Haven't looked at the lifters yet, are they likely compromised?

4) Speaking of the long tower bolts, about half of them came out of their holes milky in appearance. Please tell me these bolts pass through the water jacket and that is why they are contaminated and I do not have blown head gaskets.

5) Since I have it opened up, should I replace the oil pump? Maybe the oiling problem started there and it isn't the kids' fault.

6) What about the water pump? Renew it as well? 150K mi on both pumps. By the way, the lowest bolt for the water pump sheared off, seems well and truly stuck and I probably need to drill it out. Any sage ideas?

7) With new cams & rockers I assume there is a calibration procedure to follow setting them up. Difficult?

8) Anyone have an A/C compressor for the beast?

I suspect the engine was opened up previously because of a few things I saw that didn't look like factory work.

Thanks all...

You make an excellent argument in favor of removing the heads, and quite likely inspecting the bearings also.

[97 SL320]

I've seen bolts in blind holes fill up with oil / sludge / moisture. They probably smelled like baked oil when removed. If you don't have water in the oil don't be concerned about the bolt glop.

Running an engine low on oil for an extended period of time is far worse than having all the oil fall out at once and the crank grabbing a bearing. ( not much time to wear things out ) I'd be looking for parts cars or even a 4 door car for an engine ( if it interchanges ) as fixing everything could be $$.

[KCM]

1) Don't worry about the torque to loosen them. If they came out without stripping the threads, reinstall and torque correctly.
2) If the camshafts and rockers are that bad, I would replace the towers as a precaution since they are the camshaft bearing surface. Don't forget the plastic oiler tube fittings.
3) Lifters are probably okay. If I remember, they can be checked by pushing them down and seeing if they come back up. Check the service manual as it tells how to check them. There is a tool you can buy to adjust them. They can be replaced with the engine in the car.
5) Was the oil pressure okay? Did it max out the gauge at speeds above idle and stay somewhere in the middle at idle? If so, it is likely okay, but if it makes you feel better, you can replace it. If there is a relief valve, might what to check the spring to make sure it isn't broken.
6) Water pump. Didn't replace mine and it has around 150,000 miles now. Seem to recall they are not cheap. Again, if it gives you peace of mind....
7) There is an adjustment procedure for the rockers and lifters which require special tools to check. There are shims on the valves which are very expensive. I put the shims back onto the same valves I took them off of and everything turned out okay. Ideally you should check and change shims as necessary. The lifters just screw in and out to adjust. Again, check the service manual for the procedure.
8) A/C compressors are readily available new and rebuilt. They actually used a pretty decent and modern compressor. Bought a rebuilt for mine several years ago with no problems.

A few other suggestions. Pull the engine and take the pan off. Take a couple rod caps and main bearing cap off. If it was ran low on oil, you will find scoring on the bearings. If they look like new, then the lower end would be fine. Replace all the timing chain guides. If one is broke, I wouldn't trust the rest. Unless you know the timing chain has been replaced recently and since you are that far, replace anyway. And check the valve guides as they are a softer material than the valves. When I had mine apart found they were pretty loose so I replaced them all and ground the valves. Loose valve guides will cause oil consumption. Noticed an increase in manifold vacuum too.

For the service manual, go to the Mercedes website:

https://www.startekinfo.com/StarTek/outside/11883/?requestedDocId=11883

or

https://www.startekinfo.com/StarTek/doclist.jsp

While you're that far into the engine, do it right the first time and you won't regret it.

[97 SL320]

A few other suggestions. Pull the engine and take the pan off. Take a couple rod caps and main bearing cap off. If it was ran low on oil, you will find scoring on the bearings. If they look like new, then the lower end would be fine.

I used to do the few caps off method until I came across a 2.0 turbo VW that lost _all_ of it's oil at once due to a punctured oil pan. ( and was driven 3 + miles ). All rods / mains were perfect except for one that started to transfer bearing material to the crank. Ended up flaking the bearing material off the crank and doing a quick polish to save the engine. ( This was an in car repair and all bearings were changed ) Had this last bearing not been noticed / properly repaired, the engine would have come apart in sub 5 K miles.

[rjk]

Thanks for the detailed thoughts KCM, we think alike.
Stopped by my local MZB indie and he allayed a few of my fears which align with what you point out.

1-Indie agrees with you on that, clean the threads and reinstall.
2-We measured and looked at the towers, he said not to worry about them. I already have the plastic fittings (half of the old ones were broken, maybe the kids are off the hook again).
3-I'll check the manual and see what needs to be done if anything.
5-Oil pressure was never a concern by the gauge readout. Maxed out at 3 at speed and never dropped below 2 at idle (so maybe I will blame the kids, they're NOT getting the car back either way). But at $150 bucks, I'll think about it anyway.
6-No symptoms here so I may just reinstall.
7-I had read about that and so have not yet removed the shims so when I do, they will be properly logged.
8-Figured as much, the old one has a leak (minor but there) so I figure now is the time to replace it. It is a tight fit down there.

Pan's already off since I pulled the front cover (engine is supported by a cherry picker) so I may go under and look at the crank, especially the last bearings in the oil path.

Already have all the guides (ALL of them including oil pump chain guide) and the main chain, like I said, sounds like we think alike.

Next step is a leak down test to see about that valve and anything else that may warrant head removal.

I'll post back.

[rjk]

Well, it could have been worse.

The head showed many leaks (valve & otherwise plus 2 bad lifters) so off they came and my machine shop has fixed them up. Block is out of the car.

I have chased the block head bolt holes (lots of crap in there along with alu shavings) but have read about helicoil recommendations along with the drill guide for the off-axis bolts.

Not looking to buy another expensive tool I will only use once but...

How lucky should I feel about installation? Oil or anti-seize on the bolt threads?

I suppose I could try it and if anything strips pull off the heads again and helicoil the holes.

Another thing, are the head bolts reuseable or do they need to be replaced?

[rjk]

bump?

[BobK]

There may be a length measurement on the bolts. Don't remember for sure. Yeah, those plastic clips on the oil tubes on the cam towers are a known issue. I have a new set of them ready to go on my 107. Did that water pump bolt leave you enough to grip? I'd heat the hole with a torch to set if the hole would expand enough to get the bolt out. I have heard of having the engine warm when taking it apart to avoid stripped bolt holes and stuck bolts. I think you can rent or borrow the guide plate that bolts to the block to drill and helicoil the head bolt holes.

[rjk]

So, this project is taking longer than expected due to passing kidney stones, surgery, conferences (in- and out-of-state), end of school stuff (I teach), ad nauseum...

I am ready to reinstall the heads and have read up on the block Timesert debate. It is my considered opinion stripped threads may very well be the result of unprepared head bolts & holes. I have chased the threads in the block and the same for the bolts, no grinding when you screw the bolts in.

So the next question is this...anything special to use to lube the threads? Anti-seize, a little oil, assy lube, dry?

Am I off base with my assumptions?

[97 SL320]

When threads pull from an aluminum casting, it is due to fatigue of the thread root. This leaves you with half of a helicoil and a smooth hole. Thread friction during install seems to be what pushes it over the edge however I've seen pulled threads happen while parts were in service.

You could get a shorter head bolt, place a washer on the block deck to protect it ( like brass , copper , aluminum ) then apply full torque to test the threads. This way you don't have to go through the whole head install process to find out threads are pulling.

I'd consider it a good risk that the threads won't pull a second time when the head is installed for real. And if they do pull during the 2nd install , they probably would have failed in service anyway.

[rjk]

I'm looking at the oil pump and gasket set and see no gasket in the lower end kit. Is there no gasket for the OP? Is liquid sealer the correct medium?

[rjk]

Is there a way to pump up the hydr lifters without cranking the engine?
I'd like to measure & set the tappet shims before I reinstall the engine.
I noticed what look like oil gallery plugs at the back of the heads.
Any chance these are there for just such a pump-up operation?
If so, anyone cob together a mechanism to do so?

[rjk]

Another question
I cannot find an accurate head bolt tightening sequence anywhere
All I am pulling up are two row bolts, not the three row on my heads