I haven't been this scared since my oil consumption

[Tom McMenamin]

problem and I thought I was headed for a complete valve job. It turned out that the seals and guides fixed the problem and I dodged a bullett.

Well Guys, I am in panic mode once again. My 1988 560SL has 211000 miles all highway. This car has never missed an oil change and anything that was ever wrong was repaired practically the next day. Any of you who have read my previous posts know that I take super care of this car. It's like a child.

So here goes the problem: About a month ago car was smoking white smoke and missing. Replaced 4 Injectors on the passenger side. Replaced Radiator due to a leak. Replaced the Sensor on the Transmission to eliminate smoke. All was well! Car ran and still runs better than it has since I owned it.

About 10 days ago, I started the car and heard a loud WHACK! in front of the engine. Starter turned maybe once and nothing. Re-Hit Starter car started right up. Slight miss for about 30 seconds. Car then smoothed out and ran wonderful. From that point I got the same miss almost daily at first start. Never last more than 30 seconds.

Now...I have received an opinion that greatly concerns me... Someone advised that one of the magnets may have broken loose from the flywheel and that is what is causing the miss. Now this is an expensive repair!!! As usual I am panic stricken. What else could it be? How likely is the magnet the problem? What happens if the magnet is not replaced? Why am I still losing coolant on the garage floor? Any relationship between the miss the coolant drip etc.? Any other diagnosis any of the super tech guys might have?

I'm putting my laptop on the front seat of the car so that you can diagnose thru Mercedes Shop!

Let me know if I should be panicked?

[nobby]

The coolant leak is coming from where? How old is the water pump? Could be dripping out of the weeping hole which is a warning the seal and bearing are on the way out.
How old is the timing chain and guides? That "whack" you heard should be a concern but hard to diagnose over the net. Sorry I can't be more help.

[Lexxani]

do you get a metallic whine on startup? I was experiencing that problem when I broke a plastic chain guide in my drivers side head, that may have something to do with that 'wack' sound, if your chain is loose enough on start up to hit your cyl head.

[blacknight]

It sounds like you may have a headgasket failing. With the vehicle mileage, the white smoke and the miss, that is where I would start looking.

[Roncallo]

Originally Posted by Lexxani

do you get a metallic whine on startup? I was experiencing that problem when I broke a plastic chain guide in my drivers side head, that may have something to do with that 'wack' sound, if your chain is loose enough on start up to hit your cyl head.

I agree this is the first thing that should be checked. In fact before you even start the engine again. When was the last time you rails were replaced. Also did you replace the tensioner rail. The tensioner rail is the only rail that wears out of the 4 that can be replaced from the top. It is often not looked at or replaced because people think its hard. It's not. 30 seconds to quiet down also seams like alot. You may also need a tensioner as well.

at 210K mile you are breaking into new territory. Not too many people have gone above 200K mile so there is not a good data base to say if you are possibly reaching the limits of the lower rails. One of the lower rains pulls around a curved rail like the tensioner rail so it will also wear. The rest of the rails merely act as a backup to stop chain vibration.

My plan at 200K miles was to pull engine do all rails, timing chain and oil pump chain. Clean engine bay and reseal engine.

[Tom McMenamin]

The car spent the last week at the mechanic. Removed starter, Checked Flywheel, replaced Thermostat. Observed car for 3 days.

Yesterday morning at start the whack happened again this time not as loud and car started along with the sound. (Didn't need to shut down or grind the Starter.) Still have the miss at start up does not last as long now maybe 10 seconds.

Car runs great following the "bump" at start up and confounds me at this point.

The Timing chain was replaced along with Guides etc. at 130,000. The idiot who replaced it bent a valve and I did a top end at 130,000 miles as well.

No leaks found anywhere. Coolant and cooling system pressure has been reduced with new Thermostat. No Garage floor coolant leaks anymore. A positive.

I'm beginning to believe that it is a chain guide issue. We look at it all the time, due to my paranoia. Every time I get a repair we chack the chain etc. That's why I am doubting the chain as a problem, but I'll get it reviewed one more time.

All help would be appreciated here. By the way, the flywheel on the 1988 560SL does not have magnets. That was bad info from someone.

I'm gonna check the "Search" one more time and see what we have. All points of view graciously accepted! Thanks!

P.S.When reviewing the "chain" what are the parts that if something was awry on the chain, or guides, or whatever to check that I may have overlooked?

[Tom McMenamin]

Just started the car, White smoke is back! Stops after car reaches operating temperature. Coolant is still OK but appears down from my last check of two days ago. Pulled oil stick and I can't see any moiture contamination. The smell of the smoke is almost definietly moisture.

But when I say White Smoke, I mean White Smoke and lots of it.

So let me recap!

The problem started about two weeks ago when the smoke first started. Started car one Sunday AM after sitting for about 2 days and the White Smoke came bellowing out. Prior to the smoke, I was getting a lot of AntiFreeze on the garage floor and coolant was going out at about 1 gallon per month. Found a leak in the Radiator, so replaced the Radiator. As well, replaced 4 injectors on passenger side due to miss at idle.

Idle corrected with injector replacement, but returned at start up to miss for about 30 seconds then it smoothed out. Miss is still there at start up.

Following this service is when I heard the loud Thwack sound emanating from front of car. Smoke returned shortly after the injector replacement and so replaced the Transmission shift sensor. Felt that ATF was being sucked back into the system causing smoke. Eliminated the Cam oiler which might have occurred at injector replacement. Seemed to subside and then it returned. Not all of the time but every once in awhile on start I would get a lot of White Smoke. Again at operating temp it stopped.

Took car back to shop. Seems that the cooling system had significant pressure so replaced thermostat.

Following all of this, car expereinced another thwack sound at start. Not as loud as before but the same sound. This time I didn't need to restart as car started simultaneously with the noise. Previous 2 times it took 2 starts to get it to go following the noise. When the key turned, car would give nothing except a slight Starter turn. Everything lit up and after 2 tries car started.

Today on initial start White Smoke returned. Again at Op Temp it went away.
On return from clearing the smoke, pressure is up again on the cooling system.

Can find no leaks under the hood, garage floor almost dry. Not even any Air Cond overflow.

I must have more than one problem. The mechanic I use has always been really good. Never threw parts at a problem always went thru step by step diagnostics. Still does. Wouldn't replace the Trans sensor until we proved that nothing else seemed awry. I know this is contrary to the previous but he is a sharp guy and I trust him. I just think he is a buffaloed as me. Problem is that it seldom smokes for him, and he hasn't experienced the Thwack noise. Naturally the car performs well after warm up and runs better than ever.

Sorry to keep posting but I'm really at a loss.

[tk0084]

Well, it seems to me that if the mechanic doesn't have the same issues that you do then why not set up a video camera, start recording & then start the car. If it thwacks & starts smoking then you can get out & move the camera to other angles. Open the hood & show in there, the back end smoking, etc. This may assist your mechanic if he is unable to replicate the situation.

[Tom McMenamin]

Can't believe that I'm that stupid not to have thought of that. Maybe thats why these web sites exist because someone out there is not as dumb as me!

Great idea and thanks for your input. Truly a wise man who thinks on his feet!

[dpetryk]

Sounds like you might be leaking coolant into the cylinder after a drive. Then there might be enough liquid in the cylinder to dead head at the next startup. Dead heading will produce a whack and then the liquid is expelled on the next exhaust cycle. Then there would be a miss until the spark plug dries out. It might explain all of the symptoms you are describing. Including the white smoke while it is running. In the case where the whack is not heard and the miss is there for 30 seconds, it is conceivable that the offending cylinder is in an exhaust cycle and the dead head does not occur but the plug still gets wet. I would suspect a head gasket. If the whack is consistent, then I would remove all the spark plugs and crank the engine and see if you get any coolant blowing out the plug hole. That would be obviously where the problem is.

[Tom McMenamin]

Sounds like you might be leaking coolant into the cylinder after a drive. Then there might be enough liquid in the cylinder to dead head at the next startup. Dead heading will produce a whack and then the liquid is expelled on the next exhaust cycle. Then there would be a miss until the spark plug dries out. It might explain all of the symptoms you are describing. Including the white smoke while it is running. In the case where the whack is not heard and the miss is there for 30 seconds, it is conceivable that the offending cylinder is in an exhaust cycle and the dead head does not occur but the plug still gets wet. I would suspect a head gasket. If the whack is consistent, then I would remove all the spark plugs and crank the engine and see if you get any coolant blowing out the plug hole. That would be obviously where the problem is.
______________________________________________________________

I have to agree with your opinion. Makes all the sense in the world.

My question is what makes the whack sound. Obviously when the cylinder fires the explosion that occurs creates the sound. But it doesn't always make the noise when I get the smoke. This probably has to do with how far the cylinder is up or down at the time the car stops? Correct?

Head Gasket issues generally derive from overheating which warps the head and causes the gasket to seperate producing the coolant leak. I will assume that I have one or more cylinder leaks (probably one, thats why the thwack is so random). At any rate I'm looking at a new head or machining the old head.

Many, many thanks for taking the time to respond. Last question would be: This seems to be something that a seasoned mechanic would know. I wonder why my guy didn't suspect or know about the deadheading? If he knew why would he avoid the obvious head gasket problem? Makes me a little leery! Should I be?

[nobby]

I'm guessing he wanted to approach it from every angle before diagnosing what now seems to be obvious.
If, after shut down, coolant leaks into a cylinder, then it will have changed the displacement of the cylinder probably resulting in the "whack" sound at start up.

[rocky raccoon]

Been watching these posts and agree with the probable coolant leak. I recommend that you let the car sit overnight, then pull the plugs and crank the engine trying to find the offending cylinder by looking for the one that squirts coolant.

This is a potential massive problem. If a cylinder becomes almost full of coolant you may experience hydraulic lock when starting the engine and bending/breaking who knows what.

[dpetryk]

Deadhead is another term for a condition also known as hydro lock or hydraulic lock. It is where there is liquid in the combustion chamber and the piston cannot compress the liquid thus not allowing the crankshaft to turn. You may not have true hydro lock but the added liquid might make for some very high compression numbers which you feel as a whack. If it was true hydro lock then something has to give - usually the connecting rod or the piston crown etc. I think removing the plugs and cranking the engine will clear up the mystery.

[Tom McMenamin]

Well, I want to really thank you guys for your help. I can't be happy about the cost to repair this problem, but I was sure I had a serious problem based on what was happening. My concern now is getting it about 10 miles from here to the shop to get the work started. It should be OK unless I bend a rod starting it!

At any rate, as I work through this, it could be that the Timing Chain replacement at 120,000 might have caused this development.
Long shot, but the numbskull that did the change@ 70K bent the valves developing into a top end repair and machining on the Head. We parted company after that and referring to my stupidity in previous posts, I'm wondering if the torque was checked on any subsequent repairs. Could be that it was and over time we have arrived here. Maybe not and that ultimately put me here. Also an overheat, but have never really experienced any overheating in the last 70K. I worked in DC and my commute was 120 miles per day until 2 years ago. Ergo 70K. All I 95 expressway if you can call it an Expressway.

Matters not. Gotta get it done and hope for the best. I guess its not how it happened but what you do about it after the fact. I've always wanted to know WHY. Guess its best to just let some things lie!

I guess my last question would be... after this job is complete, what should I look for and what would be recommended for follow up maintenance.

That question probably can't be answered until we know the extent of the damage. I'll keep you all posted!

Again, thanks. Special Thanks to Dpetryk. I'll never repay this sight for the help I have received over the years! I can always count on the folks @ Mercedes Shop.com

God bless all of you!