Complexity of doing valve seals M11o - Page 2 - PeachParts Mercedes-Benz Forum

t walgamuth · #16 05-26-2006, 04:45 PM

if your valve guides are worn it will show on start up. a puff of blue smoke is all.

the other time is on overrun. rev it up in third to near redline and back off the gas fully while looking in the rear view mirror. on my 74 bmw if you ran it up to about 90 in third and backed off a huge blue cloud would puff out the back. yet it used very little oil under normal driving conditions. not nearly enough to tear it apart.

if your car has had decent care, i wouldnt expect the guides to be all that worn. and if the valves are sealing well, i would prob leave it alone.

tom w

rfitts46 · #17 05-30-2006, 12:15 PM

it does show on start up....once the engine is up to full temp...20-30 minutes
full temp meaning all the engine parts are warm the car does not smoke at alll. But on start up after sitting the night it smokes. Fixed locking system one vacuum hose running through firewall waas broken off. Spliced it and I am good to go. Bob

rfitts46 · #18 05-30-2006, 12:17 PM

I will do a leak down test first...this should tell me if the valve seats are bad?

Bob

Tomguy · #19 05-30-2006, 12:58 PM

Quote:

Originally Posted by t walgamuth

the other time is on overrun. rev it up in third to near redline and back off the gas fully while looking in the rear view mirror. on my 74 bmw if you ran it up to about 90 in third and backed off a huge blue cloud would puff out the back.

Mine does this but my top end is like new. It's white smoke which I believe is coming from the tranny modulator at extreme vacuum (probably easily 30" of vac when I back off at those speeds if it's 18" at idle). This isnt a good telltale sign of valve seals

300SDog · #20 05-30-2006, 01:10 PM

Done wet and dry compression can tell condition of the rings too. Meanwhile Bob you've probly figured this out already, but the reason you get smoke after sitting all night is seepage of oil past the seals into combustion chambers. Its not like they tighten up when the car gets heated up, you understand, more like no oil accumulation while the engine is running.

Does it smoke again at start-up after sitting for just a couple of hours? The amount of smoke and time it takes to disappear will help diagnose condition of seals and guides. Worst case scenario would be start-up smoke within 20 minutes or less after shutting it off. But at that point you'd probly be burning oil at least 1 qt per 600 miles.

t walgamuth · #21 05-30-2006, 08:07 PM

Quote:

Originally Posted by Tomguy

Mine does this but my top end is like new. It's white smoke which I believe is coming from the tranny modulator at extreme vacuum (probably easily 30" of vac when I back off at those speeds if it's 18" at idle). This isnt a good telltale sign of valve seals

my beemer was a stick.

you sure it isnt a sign of valve seal wear?

tom w

rfitts46 · #22 05-31-2006, 01:18 PM

Start up after an evening of sitting...there is enough blue smoke too be embarrassing if one had to be....its funny though there isnt blue smoke immediately more like 3-4minutes after start up. Once warm and taveling about town if it sat for an hour...I dont believe there would be any blue smoke. Still have not gotten to a leak down or compression check yet. Thanks for all the input. Would like to know more about the modulator valve on the transmission....what its function is and why it could contribute to blue smoke. Another thought is I have not checked the timing on the car yet either.. It runs pretty good so have not bothered to check it yet...but I will. I have electronic ignition. Bob

rfitts46 · #23 08-07-2006, 02:22 PM

finally got around to checking compression. Cold Dry check without fuel pump disconnected.

compression ranged from 130 to 106 psi. I will warm the vehicle up and disconnect the fuel pump for the next series of numbers.

My question is 'could valve adjustment affect the compression readings?'

If I get serious about taking the valve cover off...is their a gasket that needs to be replaced? Bob Fitts

Tomguy · #24 08-07-2006, 06:38 PM

That is quite a broad compression range. 106 is alarmingly low if you did this all in the same day with the same gauge (it's not the value in and of itself, it's the HUGE range, but anything under 110 is suspect normally). Test it again - if it's still low, then try reading the compression with oil in the cylinders (put about an ounce of oil in the cyl and get its reading - called a "Wet" test) - if the numbers go way up then you have bad rings. It COULD be just a tight valve, so check the valves on the low cyl(s) too.

t walgamuth · #25 08-07-2006, 11:38 PM

oil squirted in the cylinder will also seal a tight or slightly burnt valve according to my friend who used to run funny cars.

oh btw tomguy i withdraw my question about your valve seals. i understand about the mod valve. i dont know what i was thinking that night.

tom w

rfitts46 · #26 08-08-2006, 12:20 PM

what is a tight valve?

Tomguy · #27 08-08-2006, 01:20 PM

If you do not adjust your valve clearances properly (or havent done them in a while) a valve can be "tight" - the cam pushes down on the valve while the cylinder is in the compression stroke, allowing anywhere from a little to a lot of the compressed gas to exit the cylinder.

280Sbenz · #28 08-09-2006, 07:46 AM

i make the tool you need to compress the spring to remove the rocker on these engines.

around $60 AUD if you want one not including post

makes life a lot easier to remove the rockers and a lot cheaper than the genuine factory part.

allow 6 weeks for delivery

email me if your interested

ctaylor738 · #29 08-09-2006, 08:25 AM

No sense in adjusting the valves now. If there is an "emabarassing" amount of blue smoke on start-up that's not getting markedly better as the car is driven, then the head needs to come off and go to the machine shop.

rfitts46 · #30 08-10-2006, 11:23 AM

I plan on doing a leak down test. A couple of days ago I determined that the auto transmission was around 3/4 of a quart low. I topped it off and drove it for a day. The car was shifting from 1st to 2nd much smoother. It still puffed blue on cold start up. I thought the blue smoke left at red lights/stop signs was much improved if not gone all together. Whats confusing is when I leave work in the late afternoon to go home (20 minute ride down freeway) I get very little if none at all smoke. The blue smoke seems to be more apparent when I let the car warm up before engaging in gear. After work I typically start it and engage immediately into gear and drive home. The smoke is almost non exisient. Last night after going home I let the car sit for about 20 minutes while I ate. Then used the car to bring my daughter to gym class 10 minutes away...no smoke issue. I let it sit for one hour at her class and on the 10 minute ride back to the house all kinds of smoke at lights and in the driveway once I got home. If the seals are bad could sitting one hour leak enough oil to create the puffing.