Lots of blow by on a '1977 300D - PeachParts Mercedes-Benz Forum

jamp73 · #1 01-28-2013, 03:53 PM

Hello, I am on a budget and want my 300D to start when it’s below 50 degrees out. I am wondering if it is possible to remove the pistons and re-ring the engine without removing the crank on a 1977 300D. This would be the quick and dirty method not the preferred method. I just want to prolong the inevitable. Anyone out there know if this can be done?
Let me know.
Thanks

ah-kay · #2 01-28-2013, 04:07 PM

I am not a heavy duty engine guy, just w/e wrenching. I have done it on a 300SDL. I removed the cylinder head and the oil pan ( PITA job ), pushed the 6 pistons up from bottom and did a limited 'ring job'. I honed the cylinder slightly and put everything back. Make sure to cover the crank shaft when honing. The engine is running smooth now and with very little blow-by. The engine used to shake at idle and with blow-by smoke coming out from the vent-hole at the left back of the valve cover. The vent-hole is like a safety valve to release crankcase pressure. It was a lot of work and I did it on and off for 2 months.

kerry · #3 01-28-2013, 04:08 PM

Post a video of the blowby so we can have a sense of how serious it is. Most no-start conditions are caused by bad glowplugs. Are your glowplugs functional? The 77 came originally with loop style plugs. When one fails, none of them work.

cooljjay · #4 01-28-2013, 07:05 PM

To redo the rings, the whole engine his to be removed. I thought my engine was dead because I couldn't get it to crank over and tons of white smoke was coming out of the valve cover. I got the engine to run pretty good by soaking the cylinders with oil, replacing all glow plugs, replacing starter, replacing battery and cables and adjusting 2 tight valves plus adjusting linkage and synthetic oil changes. I have had no problems starting it now and my blow by has went down! On my 1982 I had, I managed to get all the blow by to disappear after around 3 years of regular maintenance and driving.

NC-Diesel · #5 01-28-2013, 07:47 PM

I have to agree. I have an 82 240 that came to me with tons of blowby, smoking, and could barely go to 45MPH. I replaced the injectors, and ran algicide and fuel additives for months. Replaced the glow plugs and the valve seals and adjusted the valves every 3000 miles. Went through boxes of fuel filters till all the gunk and algae was out! I fired it right up at 29 degrees after it had been sitting for months the other day and after warming up it had harldy any blowby with over 160k on the engine. I think proper oil changes, valve adjustments, and just generally taking care of one helps a LOT usually when we get these cars they have been neglected for years.

layback40 · #6 01-28-2013, 07:53 PM

Quote:

Originally Posted by jamp73

Hello, I am on a budget and want my 300D to start when it’s below 50 degrees out. I am wondering if it is possible to remove the pistons and re-ring the engine without removing the crank on a 1977 300D. This would be the quick and dirty method not the preferred method. I just want to prolong the inevitable. Anyone out there know if this can be done?
Let me know.
Thanks

Tell us more about the car.
Has it been running on WVO or any other alt fuel?
Mileage?
Maintenance history?
Seldom does worn rings stop them from starting unless there are other issues.

jamp73 · #7 01-30-2013, 11:59 AM

Well I'll tell you about the car. I got it from the original owner in Oklahoma in 2007. I have done lots of work to it. The person I got it from gave me a work history of the car about an inch thick, the car has had an issue with hard starts since about 80,000 miles, and the people got a letter from the dealer stating that due to age it would be hard to start from now on. (I will have to dig that up) If I was the dealer, I would have repaired the car myself.
New Starter, alternator, battery, Injectors, fuel filters, Fast Glow upgrade, tires, brakes and lots of suspension components. Vehicle has absolutely no rust, and a straight body.
I have not done a compression check, I suspect the rings because of the blow by in the valve cover. When I remove the oil fill cap, it feels almost like exhaust coming out of there; not a lot of smoke in there however.

To Kerry: I wont be able to get a video of it running at least till spring, I am in North Dakota and wont even try to start it till its 60 for a couple days.

This car has 178,000 miles approximately on the odometer. When I got the car I had to have the odometer repaired because it wasnt turning.

On a good day I still have to cycle the glow plugs twice to start it.
Also if I keep the car between 65 and 70 MPH on the hiway it gets up to 30 MPG, and averages 21 MPG in town. I can still get it up to 100 MPH if I push it on a long straight away.
This car has never run on anything but diesel, no veggie oil. I am however thinking about it after I get it running correctly.
Well thats all the info I can think of right now. Hopefully it is enough to get a couple diagnosis'.
I appreciate the help.
Thanks

BodhiBenz1987 · #8 01-30-2013, 07:46 PM

Quote:

Originally Posted by jamp73

I have not done a compression check, I suspect the rings because of the blow by in the valve cover. When I remove the oil fill cap, it feels almost like exhaust coming out of there; not a lot of smoke in there however.

As others have suggested, I would check the compression before assuming it's bad on account of the blowby. My 240D has a substantial amount of blowby (cap won't stay on), but the compression is not awful (320-320-340-340), and it starts reasonably well in some pretty chilly weather (knock on wood). When I first got it I thought it might be kaput due to hard starts, but making sure the glow plugs were working and doing a valve adjustment made a world of difference. It also helped me to replace the idle control cable, which was not working.

kerry · #9 01-30-2013, 12:43 PM

Does it have a block heater? Most had the heater even if they didn't have the cord. Have you tried starting it with the block heater activated? Have you run a diagnosis on the glow plugs?

jamp73 · #10 01-30-2013, 01:04 PM

Quote:

Originally Posted by kerry

Does it have a block heater? Most had the heater even if they didn't have the cord. Have you tried starting it with the block heater activated? Have you run a diagnosis on the glow plugs?

I have tried a block heater, however was not convinced it was working. I dont mind using one, however I want it to start without one if needed. I did install the fast glow system with new plugs a couple years ago. That helped get it started, but didnt cure it. I have not checked to make sure those plugs are still good. I think they are though, because I dont get billowy white smoke when its trying to start, and its avalability hasnt changed.

kerry · #11 01-30-2013, 01:29 PM

I would do a compression test. The HF diesel compression tester is inexpensive and easy to use in the glow plug holes. If the compression turns out to be fine, then tracing down other problems would be in order. This of course presumes the glow plugs are ok.

The dealer explanation is totally BS.

Biodiesel300TD · #12 01-30-2013, 01:34 PM

You didn't list valve adjustment. Has that been done recently? It should be done before a compression test too. Tight valve clearances cause leaky valves and poor compression.
Your location might yield a nearby forum member that could help as well.

barry12345 · #13 01-30-2013, 01:37 PM

Quote:

Originally Posted by kerry

I would do a compression test. The HF diesel compression tester is inexpensive and easy to use in the glow plug holes. If the compression turns out to be fine, then tracing down other problems would be in order. This of course presumes the glow plugs are ok.

The dealer explanation is totally BS.

I agree it is almost mandatory to do a compression check as you need a baseline to go from. It may even be something minor in nature but you have to have some ideal of the engines overall compression.

Do check the valve lash before anything if you have not. Especially prior to a compression check. All you have to be initially sure of is that there is at least some clearance between the cam lobe and the valve rocker. When the lobe of each valve is in the correct position to do so.

kerry · #14 01-30-2013, 01:48 PM

The problem with doing the valve adjustment prior to the compression test is you won't know whether or not your valve adjustment changed the compression. I'd do the compression test first, then the valve adjustment, then the compression test again.

jamp73 · #15 01-30-2013, 07:14 PM

Quote:

Originally Posted by kerry

The problem with doing the valve adjustment prior to the compression test is you won't know whether or not your valve adjustment changed the compression. I'd do the compression test first, then the valve adjustment, then the compression test again.

Good advice, I will do the compression check before and after a valve adjustment. It will however be in a month or so due to the weather.
Thanks All!

Now, will I need any special tools for that valve adjustment?