missing on cylinder

[Cees Klumper]

One engine I disassembled last year had been rebuilt by a PO and had two or three burnt valves. A small "V" like glennard describes. I will try to post pictures when I get a chance.

Cees Klumper in Amsterdam
'69 white 280 SL automatic

[rwmastel]

I'm bringing this thread back from the dead.

Update:
I got back to my car today for the first time since mid-November.  To review, I had 40psi compression in #5 cylinder and a low 120psi to 130psi in the rest of the cylinders.  I re-torqued the head bolts and adjusted the valves on #5 cylinder.  I never got everything put back together until today.

Compression needs to be tested on a warm engine, so I fired her up and went for a short drive.  I knew immediately that things were better.  After the drive, compression on #5 tested at 105psi.  Still  very low, but much better.

Outside of an overhaul, what does the Group suggest I do now to improve my compression?

Thanks,

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[Malc]

Rod,
From your update: I am assuming that you did not take the head off.
Form all the other posts some possiblities spring to mind:

[li] Valves on 5 may not be burnt out but are not seating properly[/li]
[li] Above would happen as deposits build up on valves that don't completely shut [/li]
[li] Bent valve or valves [/li]

However you state compression has gone up from 40 to 105 and the rest are around 120 - 130 so your within 15 - 25% of the rest.

In order to improve compression I would....

Take off head.
Remove valves check seats and valves
Clean head and valves inspect valve seats and valves replace if required.
Lap (grind) valves in. Use a little engineers blue to check seal surface on the seat.

and while head is off
Check bores for size and "Ovality". Measure Bore diameter about 2/3 way down with the piston at the bottom of the stroke and 90 degrees apart. Check within limits

How many miles on your car? Might need new piston rings.....

HTH
Malc

[rwmastel]

Malc,

Thanks for the advice, it's what I expected but didn't want to hear.

I know I need to do valve work as the car burns oil out the exhaust (blue smoke).  Also, I know the bottom end bearings are worn as I had the oil pan off once and removed the bottom half of the front two bearings and they were worn/scored.  It would not suprise me if the cylinders were a little oval.  Milage on the car is unknown, but the timing chain that was removed last year was not a factory original chain.  I'm assuming it's got about 230,000 miles (368,000 km) on it since this is (at least) the second replacement chain and they last about 100,000 miles each.  The Euro odometer reads 68,000 km right now, so that also was an input to my guess on the milage.

I'm trying to hold off on a major engine overhaul as long as I can because once I start that, then I'll want to do other things:

- refurbish automatic transmission
- rebalance drive shaft, inspect for worn parts
- replace leaking seal in differential
- refurbish rear axle seals and bearings
- replace full exhaust system

So, should I leave it parked, drive it like it is, or are there some more simple things I can do to improve the health of my engine compression?

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[George Davis]

Rodd,

I doubt there is anything you can do to further improve compression without disassembling the engine.  I say drive it, but don't flog it hard and keep a close eye on all fluids, and maybe do compression checks every now and then to see if cyl 5 is changing.

George Davis
'69 280 SL Euro manual

[rwmastel]

quote:Originally posted by George Davis

Rodd,

I doubt there is anything you can do to further improve compression without disassembling the engine.  I say drive it, but don't flog it hard and keep a close eye on all fluids, and maybe do compression checks every now and then to see if cyl 5 is changing.

Thanks George,

I do plan on changing all fluids next month and doing some other normal maintenance.  Monthly compression checks will be in order until a rebuild occurs.  Ever since I've owned it, it's rarely been over 4,000 rpm, never past 5,000.

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[Malc]

Rod,
Definitely agree with George. Just keep driving the poor old dear, just be gentle!
You would be amazed how long you will keep going as long as it doesn't start to drink both water and oil in excessive quantities
you should be ok
Cheers
Malc

[rwmastel]

quote:Originally posted by Malc

You would be amazed how long you will keep going....

I'm amazed that it's gone this long!

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[Tom230sl]

Pull the engine.
Ship it to Metric Motors.
Pay him $5800 fot a long block.
Reinstall.
Problem(s) fixed.

[Malc]

Tom says $5800 for a long block, I assume that means you get a reconditioned engine with a cylinder head but none of the plumbing, starter, flywheel, fuel pump etc

Or

You can get down and dirty, make a mess, dribble oil everywhere, and strip the engine yourself. If your really sneaky you can work on parts on the kitchen table, just don't get caught!

On a more serious note you know that you only have your self to blame if it goes wrong, you learn more about your car, and you get to keep your original engine
Just a thought
Malc

[ja17]

Hello,
You both will need to identify the problem of the low compression before you consider fixes unless you decide to go for the for the total rebuild.

Joe Alexander
Blacklick, Ohio

[Naj ✝︎]

Anybody try this:

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&category=10398&item=4542322883&rd=1

naj

65 230SL
68 280SL

[rwmastel]

quote:Originally posted by Tom230sl

Pull the engine.
Ship it to Metric Motors.
Pay him $5800 fot a long block.
Reinstall.
Problem(s) fixed.

Tom,
My engine (and transmission, differential, axels, and steering box) is original to the car.  If I were to do this, I would want mine back so I have the right engine number.  Preferrably, I would like to rebuild it myself to gain the experience and save the money.

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[Tom230sl]

Well, it was just a bit of  joke. But yes, Mike at Metric would redo your block & head, check for and weld any cracks, check the tolerences, and genealy put everything right from the valve cover down to the oil pan. He did my 230 engine. Actually, I think his price is more like $4800, but check with him to be sure www.mercedesengines.net or (818) 712-9881.

[mdsalemi]

quote:My engine (and transmission, differential, axels, and steering box) is original to the car.  If I were to do this, I would want mine back so I have the right engine number.  Preferrably, I would like to rebuild it myself to gain the experience and save the money.

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

Rodd,

Metric has, in the past, performed mostly exchange engines.  If you send him yours (doesn't sound like this will happen tomorrow) you need to make certain they give you the same head/block back, and that they DON'T grind off the serial numbers to replace with their own.  This has happened in the past, though we ensured it did not happen with mine.

With JA17 in your neighborhood, it might be something to try...however, Metric (and Noel's in Florida) does engines for a living.  They have all the special tools techniques and more experience in engine rebuilding then all of us combined since they do it exclusively.  My personal preference is to defer to experience.  Add up all the parts costs first to determine just what you might be saving...

Michael Salemi
1969 280SL
Signal Red w/Black Leather
Restored