What would you do with this 200k oil guzzler?

techguy

Hello team.

Been a while since i've been round here, but interested to hear peoples opinions on something I have been contemplating for a while.

I have a 200k mile E 350 Petrol Merc that I have owned for the last 10k miles (it was a good deal). It's a 2010 estate and has the M272 CGI engine.

Basically it burns a lot of oil. I don't have hard numbers and must do some new measurements after some repairs and oil change but it used to be in the litre for 700 - 1000 mile range.

I have since changed the PCV valve which was speculated to contribute fair bit so need to re-assess. The entire PCV system (external) parts have been changed now and still burning. I have also stepped up the oil from 0w/40 which was in all the service history and what I put in when I bought it. I am now running 5w/40 which seems to have helped a bit.

I have also concluded that it is probably more valve stem seals than piston rings. Starting in the morning results in a puff of white(blueish) smoke. Also, if I sit around in lots of stop/start (London rush hour) traffic or idle for ages.. then go the bottom of a hill and floor it in 1st gear, I get an absolute megaton of smoke. On two occasions trying this I managed trigger a misfire. I have concluded that the massive vacuum formed at idle/low revs is sucking oil into the cylinders.

Please note I am a DIYer so do a lot of the more do-able stuff myself.

The two solutions I see now are:

1) Get down and dirty with the engine and rebuild either the head or go all in and do the block also. Could be a few grand but with a like new engine probably good for another 200k miles. I would enlist professional help for this. And not yet quoted the cost yet either.

2) Draw a line in the sand with the engine and don't spend any more money on it. Try the use of additives and thicker oil (10w/xx) to the slow the consumption and see how long I get out of it before it burns the cats. Could get another two years easy, I guess @ 5-7k per year.

It's a tough one, because the cost effective, bangernomics approach says option 2 is best. I just don't like idea of driving something into the ground and dogging an engine like that. I also simply love the car, great spec silky engine and don't really want to go back to the drawing board to get another as they are pretty rare.

I have been advised that a good middle ground is to purchase an engine from somwhere and drop it in. I don't really think that is a good idea as it's an unknown engine and could develop it's own faults over time. And the cost of acquiring one of those engines and fitting wouldn't be massively less than option 1 above imho. (Rare engine).

What do people think?

Tea drinker

It's not a small undertaking to rebuild an engine and that big lummox is going to be harder again.
OTOH Have built a few engines down the years and thouroughly enjoyed it. Some I rebuilt myself, some I split the bottom / top end and got a an engineering company to rebore / grind valves / new guides etc.
As a compromise position you might try see if someone could change the stem seals without pulling the heads.
That's a gamble if the valve guides / valves are worn themselves. So it depends how cheap you can get it done.
Finding the typical wear points for that engine is valuable knowledge which can help guide you to better gambles :-)

You have already done the PCV system and that was the cheapest easiest gamble you (or anyone) could have made.
Did you pull the cam covers? in case any mesh or breather pipe is blocked? Try disconnect the breather when the engine is running is much blowing out? Is there much blow by when you open the oil filler cap?
The next cheap gamble would be running a good engine flush through it, and running the likes of dipetaine through the fuel system to help remove combustion chamber carbon, maybe unstick a few rings

techguy

Thanks @Tea drinker

I remember opening the filler cap before with the engine running and nothing blew out on me.. I will check it again.

I guess I could potentially do the valve seals (I would try it myself) but I don't fancy the chances of just that. If going at the engine I would rather get a full overhaul then and be confident. I must price it up.

I will investigate the PCV pipes, like you say.

I think the next course of action for me is to try and perform an accurate oil consumption test, like MB refers to. Then try something like additives and potentially thicker fuel. For me thicker fuel is a last resort as I do lost of short journeys meaning plenty of cold starts and extra wear.

What do you think of my argument of paying to rebuild as opposed to dropping in a donor engine. I would want the donor engine to be 40-50% of the cost of engine rebuild because it may need it's own work doing not long after. If it was going to be any more then i'd just rebuild mine and have it like new again.

Tea drinker

check out what the cap dance is like on the filler cap maybe it won't blow out oil but good to see what the pressure is like in that crankcase https://www.youtube.com/watch?v=-VdiYF_ldbk&feature=youtu.be

A compression test might be useful....
I'd try "snake oil" solutions first before throwing money at a rebuild or replacement. Either option would be expensive.
If compression is good and a "real" mechanic agrees on the approach then changing the stem seals alone might be the job for you.
Might be a head(s) off job with that engine as opposed to macgyver job of pressurising the cylinder with compressed air via spark plug hole.

spiggotpaddy

I'd try an oil additive, its cost very little and won't make it any worse. We had a cheap motocross with a gouge going right across the piston skirt, making it nothing more than a smoke machine, so just for craic tried a bottle of oil stop leak and couldn't believe it. It was still smoky but usable. If you rebuild it you take the risk of falling down the domino effect rabbit hole. The auto box is probably not far behind.

techguy

Thanks guys..

I had a look at the engine oil filler with the the engine running today. Bit of splutter which I would expect, given the direction of the chain. Nothing major as per the video linked above. When I put the cap down, it moved but more so due to idle and not being blown out under pressure.

What do people think of the video?

All advice and logic points to driving this thing into the ground and just throwing magic potions and thicker oil at it.

I'll save my hard earned for the R230 SL 500 which like sneak into the old pocket

Tea drinker

Not a lot of pressure on the cap evident there, good sign. See if you can get a garage to quote on changing the stem oil seals without pulling the head, or google the heck out of how to do it yourself. I found some vids of guys doing it on older V6 mercedes, but your heads could be chalk and cheese in comparison. Seems people whinge about how long it takes so brace yourself either way.
OR! Get the snake oil in!
https://www.youtube.com/watch?v=wcquNCrRxyA

https://www.youtube.com/watch?v=smRjx5Ykgqw

Look, If you like the car get a quote to get if fixed properly, maybe it won't be prohibitively expensive and you'll know it's done right.

techguy

Tea drinker wrote: »

Not a lot of pressure on the cap evident there, good sign. See if you can get a garage to quote on changing the stem oil seals without pulling the head, or google the heck out of how to do it yourself. I found some vids of guys doing it on older V6 mercedes, but your heads could be chalk and cheese in comparison. Seems people whinge about how long it takes so brace yourself either way.
OR! Get the snake oil in!
https://www.youtube.com/watch?v=wcquNCrRxyA

https://www.youtube.com/watch?v=smRjx5Ykgqw

Look, If you like the car get a quote to get if fixed properly, maybe it won't be prohibitively expensive and you'll know it's done right.

Thanks again @Tea Drinker !

I will be relocating back Ireland for a few months in the next couple of weeks and I will be doing some proper cost analysis on various levels of engine work. Fantasy here in London!

I've googled the heck out of it already and the job looks doable in theory, just not 100% about my particular engine as it would be hard to get rope into the spark plug slots. I would be confident about DIY'ing the stem seals as I should be able to do it without the need to remove the cams and thus not needing to re-time the engine.

I have seen that Forté stuff before and that video. I believe it's good so might give it a shot before tinkering with the engine. I believe it takes up to 6k miles to work and I only do about 5k a year in the UK, probably a bit more in Ireland.

I think my first set of actions will be various additives and a carbon clean via additives as opposed to that gas recirculation method. There could be significant carbon build up and I don't want to risk large chunks ending up in the wrong places..