Rebuilt Engine...Smoking Already

[Allen F]

Hi Folks,

I just rebuilt my 230SL engine with new sleeves, rings and a complete head job and it has started smoking worse than before.  It seems to be coming through the valve guides, and I have seen some discussion on this.  I had heard at one point that there was a newer design seal on the 280's that was better, but I am not sure they can be retrofitted.  Also, my freshly rebuilt enging only has about 148lbs of compression.  Does this sound right?

HELP.  Thanks to all in this forum.  Here is a thermal image of my 230SL.

Allen Frechette

Download Attachment: 23sl.bmp
78.33 KB

[Cees Klumper]

You can check whether any of the seals have popped off by taking the valve cover off and peering through the valve springs, with a flashlight. You had the block resleeved? What tolerances did you have them machined to, and what size pistons?

Cees Klumper in Amsterdam
'69 white 280 SL automatic

[Malc]

Allen,
Agree with Cees but other things to check/think about

When you put new rings in did you check the gaps with a ring in the bore? check closure with feeler gauges
Did you get the bores honed to produce a "cross hatch" pattern. You should always do this as the rings need this to help them "bed in"

Sometimes a new engine will smoke for a while as everything beds in. Has your oil consumption gone up, also what oil are you using? if you use a modern 0 -40 or 15 - 40 it might be too thin. I usually use a good quality 20 - 50 for the first 500 miles and then change it and the filter use the same stuff for another 1000 miles and then change the filter again.

I assume you cleaned out all the breather pipes and hoses flame traps etc

I am not sure about the actual value of the compression, but the important thing is are all the cylinders within say +/- 20psi.

Finally smart picture! were you using infra red film or a special digital camera??

Malc

[Ben]

I had a similar thing and it WAS the valve stem oil seals. Three had popped up but the only ones available are the standard white plastic type. The later 280 type wont fit. You should check it as Cees says and if you find they are up you could try popping them back on with a screwdriver but I suspect you will end up replacing them.......I did !

There is a tool, discussed here previously which enables you to fit seals without head removal, the cars head not yours !  you need to ensure the guides are completely dry and oil free before attempting to install these new seals.

Also you should use mineral oil until the engine is run in otherwise the components will never setlle properly if you have used a synthetic oil straight away !

Regards,
Ben in Ireland.
'64 230SL 4sp.
'03 CLK Kompressor

[Joe]

I suspect the other guys are right about the seals, but if you did not stagger the piston ring gaps, your car will put volumes of oil into the intake manifold and out the exhaust pipe. It seems like a silly thing to do, but it really is necessary.
Joe2

[jlennon3]

I just recently rebuilt the M130 fuel inj engine in my 108 chassis. Aligned the rings properly, checked gaps and had the cylinder walls honed. My engine smoked some initially, not a lot, noticed it mainly when I was decelerating. The amount of smoke decreased as I racked up more miles on the engine to basically no smoke after about 300 miles.

Maybe you just need to give your rings time to properly "bed in"???

John
280SL
280SE

[n/a]

Here's another one.  Just finished the rebuild and the thing is becoming a smoke monster already.  Has less than 100 miles on the build, turned ot over to the owner for some fall color enjoyment and it started smoke ten miles from the house.  Ran fine at cruise, let off the gas and it's ok, but then hit the gas after coasting and it puts out a smoke screen.  Checked the timing and it had managed to go to 18 degrees with the vacuum off (owner said he reset the points, but didn't recheck the timing).  I reset the timing to 14 BTDC without the vacuum (where it ran best for me).  Checked the plugs, #2 oil fouled, the rest are a little lean.  Popped the valve cover.  The seals, white teflon are still on the valves,  Removed the #2 intake spring and the valve is tight in the guide.  Put it back together and checked the valve lash.  Still good at 3 and 8 so what else can I play with?  Going to check the compression tonight.

'68 Ranchero GT '88 5.0 EFI 5-speed stock  

'93 Mustang LX hatch 5.0 5 speed, 10-1 CR, 73mm C+L MAF, SN92 Paxton, 3" SS power pipes, 65mm TB, Ported + Polished GT-40 intake, 24lb injectors, AFR 185's, 1.60 FMS rockers, Crane 2030 cam, Total Seal rings, SAAC valve covers, 1 5/8" BBK Longtubes, 2.5" custom X pipe, MAC 2.5" Catback 3" tips, 3.55 gears, ROH rims, Calypso green.

11.78 @ 118mph with 1.7 60' times, 390hp @ 5,800rpm and 400lbft @ 4,200rpm (Torque Monster 302)

Currently rebuilding a '71 SL

[A Dalton]

When smoke blows out exhaust after throttle plate has been closed and engine has decelerated the car, it means that the engine has sucked a fluid in due to the  high vac created by the throttle being closed while the engine still has some rpms...
 So, it  most commonly is rings or valve seals/stems , but I have also seen it to be brake fluid from booster or trans fluid from the modulator..
 and on 113s in particular, it can be from the valve adjuster ball studs .. these must be doped when head work is done as the threads go through to the head runners....
 just a few overlooked ,  odd-ball things to check ...

[ja17]

Hello Allen
Read your spark plugs they may give you a clue. MD has the right idea. Check the compression to see if it is even. The  piston rings may take some miles until they completely seat and mmaximum compression can be read.

Joe Alexander
Blacklick, Ohio

[Malc]

quote:Originally posted by A Dalton

 on 113s in particular, it can be from the valve adjuster ball studs .. these must be doped when head work is done as the threads go through to the head runners....
 just a few overlooked ,  odd-ball things to check ...

Er sorry but what are head runners in Limey speak?
and when you mean doped do you mean thread lock or grease or other illegal substances???
Malc

[A Dalton]

Yeah, the Illegal substance is Thread Sealant Compound , Yank slanged  Dope, although I would not smoke it..
 ..and as the threaded mounting holes  for the ball studs go thru the head into the port cavities,[ Runners], oil from the valve train can get to the cylinders by creeping down the theads.. just the same as it can creep down through bad valve stems/seals.

 So , just as one would use a sealant on water pump mounting bolts where the holes go through into the water cavity, same goes for the  ball studs.

[n/a]

As much as I hate to hijack Allen's thread, here's a little more info that I hope helps him too.  Ran a compression check, all cylinders except #2 were 195-200psi.  #2 was 225psi(presumably from the oil soaked rings).  Put it all back together and even cleaned the plugs (bosch 7 temp range), fired it up and it seems to run fine only I can hear a rocker tapping and the motor shakes and shimmies a little.  Luckily my Haynes manual is in PA at the owners house so I have the priviledge of asking how you guys set the valve lash and where do you set it with the motor in the car?  When I built it on the stand I set the lash to a tight 3 on the intake and 8 on the exhaust between the cam and rocker.  Is this correct?  Either way I plan on borrowing a dial indicator from work tomorow and checking the cam.  I did notice withthe engine cold that I have about 3/4" of low side of the cam that doesn't show rocker contact (from the way the oil is spread on the cam).  A comment on the ball studs...  From what I see, the only ball stud that made it to a air path was for the exhaust valve which under a backpressure load should have positive pressure keeping oil from running into it while running (My problem was oil smoke while running, but clean on startup hot or cold).  Any info or insight is appreciated.

Jamie

[TheEngineer]

I rebuilt a Rambler one time and used detergent oil. The rings never seated. Had to pull the head off and clean the bores with AJAX. Then used non-detergent oil and the rings seated just fine within 20 miles of driving. Changed the oil after 1000 miles and had the car for many years.

1969 280SL,Signal Red, A/T, P/S, A/C, Both tops, 3.27 axle. Retired engr. West Seattle, WA

[A Dalton]

The cam clearance is measured between the cam lobe and rocker .
 If you turn engine over until that lobe is facing  all the way up from the rocker , the cam base circle will be at the  proper rocker  adjustment position.
 If it is tapping , I would check that ball stud to see if it has loosened in the head.
 If you suspect the rings in that cylinder , just do a compression leak down test and listen at the breather ..compare it to the others for leak rate..
 Prob just needs seating...aside from the tapping ..

[Allen F]

Hi Folks,

I guess I must not have the alert on the forum, or I would have checked back sooner. Thanks for all the feedback.  The smoking does seem to be related to the valve seals, which were new, but they were installed by the machine shop.  Even though the guy was familiar with the engine, he isn't up to speed on the seals popping.  I have no idea if he clocked the rings as mentioned.  Under hard acceleration there is no smoke, and it runs very well.  So it looks like we will have to try to get the seals back on when the weather gets crappy.  I definately should have used a thicker oil at the initial break in, but she has 20-50 in her now.  I haven't even put 300 miles on it yet, so hopefully I will notice some improvement in performance after a thorough break in.  Thanks again for the support.  I will report back with a conclusion to the tale soon.

Allen Frechette

[TheEngineer]

I just looked at a cylinder head 230/250 and observed that only half (six) of the valve adjuster ball studs  penetrate into the exhaust passages, the other half (six) penetrate into the space above the spark plug access.
It appears that, even if there were oil leakage past these threads, it would not reach the combustion chamber. Of course it is a very good idea to seal the threads to minimize oil loss.
I'd be very interested, Allen, to hear when you finally eliminate the smoking and what you determined that caused it.


1969 280SL,Signal Red, A/T, P/S, A/C, Both tops, 3.27 axle. Retired engr. West Seattle, WA

[A Dalton]

..If the spark plugs have oil around the base gaskets , the ball studs above the plugs are suspect [ as is the valve cover gasket]
 If the exhaust smokes and plugs are not fouled, then the ball studs on the exhaust runners can be suspect.
If smoke is coupled with oil fouled plugs, valve seals/stems are suspect.. [ along w/rings.]
 Worn seals/stems usually show up right at cold start,as the oil has leaked into cylinders overnight, whereas ball studs show more after engine warms , as it is the heat of the exhaust that causes the smoke from stud leakage..
...if the studs are leaking on the plug side , it is a good indicator that the other side is also leaking.

[n/a]

Reset the valve clearance per Mr. Daltons specs and all except #3 intake were .002 tight.  #3 intake was loose...  When I built it I had indexed the distributor to the crank and did the pair of valves when the rotor pointed to that cylinder, same as I have always done on American cars and was surprised at the difference in clearances.  Put it all back together and fired it up.  Motor seemed happier, not quite as much shimmy at idle.  Took it out for a test run less hood and it ran as good as it had before if not better.  After a twenty minute run I parked it back in the garage and pulled the plugs.  All were fine except #2 which was just soaked with oil from inside the cylinder.  I guess with MB's front oil return setup any puddle of oil can either flood over the valve seal or get sucked up behind / under it.  This happened on my '93 stang with the same teflon seals.  When Air Flow Research created the heads the cutting tool for the outside of the valve seal stem was left touching the stem when it was removed making a fine spiral path for the oil to suck up under the seal.  Guess Thursday I'll get the viton seals I put on the AFR's for the Benz.  I appreciate the help.

One quick question, what are these motors supposed to sound like?  At cruise less hood it sounds like a sewing machine (mechanical bliss to me), but my customer was dismayed with the mechanical rocker sound.  Should these cars be as quiet as the new benz or are they more of a enthusiast type car with mechanical sounds?  Curse of being a Benz virgin

Jamie

'68 Ranchero GT '88 5.0 EFI 5-speed stock  

'93 Mustang LX hatch 5.0 5 speed, 10-1 CR, 73mm C+L MAF, SN92 Paxton, 3" SS power pipes, 65mm TB, Ported + Polished GT-40 intake, 24lb injectors, AFR 185's, 1.60 FMS rockers, Crane 2030 cam, Total Seal rings, SAAC valve covers, 1 5/8" BBK Longtubes, 2.5" custom X pipe, MAC 2.5" Catback 3" tips, 3.55 gears, ROH rims, Calypso green.

11.78 @ 118mph with 1.7 60' times, 390hp @ 5,800rpm and 400lbft @ 4,200rpm (Torque Monster 302)

Currently rebuilding a '71 SL

[Ben]

Well I have heard many people, both owners and dreamers compare the sound of my engine to a sewing machine.

There should be no tapping or rattling but there is definitely more mechanical noises to them than a modern car !

Regards,
Ben in Ireland.
'64 230SL 4sp.
'03 CLK Kompressor

[A Dalton]

Sewing Machine normal clatter of a mechanical lift valve train..
 However, if one sets the valve clearances to specs and finds the noise to be beyond norm, a very probable cause is that the ball stud tops are worn . You will notice a little bump/**** on the top of the ball . This is cuz the ball itself has worn down and the bump is left there from the hole in the rocker socket. [ no contact there]
 So, the valve adjustment can not be held due to the crown on the ball.
 Dan C has a good post in the archives on grinding this off to relieve the condition on a valve grind machine, but if they are real bad, replacemnt is in order and can be done to just the top portion without  removing the bases..[which can be a pain]...
  A note on adjustment :
 Some manuals recommend adjustment of each set of valves  on TDC of the compression stroke.. this puts the cam past the beginning/end of the lift sector of the cam, but I have had better luck  doing each one individually with the cam lobe facing directly up from the rocker..this assure you are at base circle of the cam.  I use a remote starter switch to make it easy.. if using the starter to turn engine , it is best to disconnect the wire at the CSV  so you do not load up with fuel..
I also clean the cam surface before adjustments...

[n/a]

Ball stud mounts are milled flat on mine.  Old cam was tore up pretty bad from the oiler bar being fouled with junk.

'68 Ranchero GT '88 5.0 EFI 5-speed stock  

'93 Mustang LX hatch 5.0 5 speed, 10-1 CR, 73mm C+L MAF, SN92 Paxton, 3" SS power pipes, 65mm TB, Ported + Polished GT-40 intake, 24lb injectors, AFR 185's, 1.60 FMS rockers, Crane 2030 cam, Total Seal rings, SAAC valve covers, 1 5/8" BBK Longtubes, 2.5" custom X pipe, MAC 2.5" Catback 3" tips, 3.55 gears, ROH rims, Calypso green.

11.78 @ 118mph with 1.7 60' times, 390hp @ 5,800rpm and 400lbft @ 4,200rpm (Torque Monster 302)

Currently rebuilding a '71 SL

[Allen F]

I will print this string and bring it with me to the mechanic.  It is Lakeside Motors in Portland OR, and the guy is a veteran MB mechanic.  I promise to post the final results.

As an FYI, I got the sleeves from Metric Motors in CA, and my mechanic said that was a smarter fix than boring the cylinders over becuase that process doesn't exactly leave a lot of meat between the cylinders, and it might eat gaskets.

I will also run the tape on the expense so that others can see the bill for such an expense, not that I am counting.  This car turns more heads than my pals Viper.  Of course, that's on the rare occasion that they occupy the same space. Keeping up with a Viper isn't something I can do in the SL.

Allen

[n/a]

Allen and others, I think I figured out my oil consumption problems.  Showed my machinist the teflon valve seal on #2 intake and we agreed that it didn't appear damaged.  He suggested that I put a thin bead of RTV silicone around the circlip to isolate oil leaking between the head and guide itself which I did to no avail.  He also said that if it's oil coating the spark plug after only about ten minutes of run time that it's almost like the motor is pumping oil into the chamber and that got me to thinking about all the extra holes and threaded sleeves MB puts in the block to hold the mess together.  Pulled out the torque wrench and retorqued the head to 80ftlbs hot.  Turned out the bolts between #1 and 2 cylinder bores were loose compared to the others (about 1/4 turn to torque).  Released and reset each bolt twice to 80ftlbs and took it for a test run without any blue smoke and the plug was oil free back in the garage.  Maybe it fixed it...

'68 Ranchero GT '88 5.0 EFI 5-speed stock  

'93 Mustang LX hatch 5.0 5 speed, 10-1 CR, 73mm C+L MAF, SN92 Paxton, 3" SS power pipes, 65mm TB, Ported + Polished GT-40 intake, 24lb injectors, AFR 185's, 1.60 FMS rockers, Crane 2030 cam, Total Seal rings, SAAC valve covers, 1 5/8" BBK Longtubes, 2.5" custom X pipe, MAC 2.5" Catback 3" tips, 3.55 gears, ROH rims, Calypso green.

11.78 @ 118mph with 1.7 60' times, 390hp @ 5,800rpm and 400lbft @ 4,200rpm (Torque Monster 302)

Currently rebuilding a '71 SL

[n/a]

double post :x

[A Dalton]

MD

 That makes sense...
   ...leak down test prob would have helped on this one.