Could using the wrong oil (non C rated) have ruined my 240 engine? - Page 3 - PeachParts Mercedes-Benz Forum

vwnate1 · #31 01-09-2019, 11:29 PM

Do the leak down test ~ if the valves are the problem, do a valve job and it'll prolly last another decade .

If it's the rings set it aside and see if a good used engine doesn't turn up ere long .

My '82 240D's #1 exhaust valve got to zero clearance, I couldn't adjust it at all, drove it like that for well over 20,000 miles including a *very* slow cross country trip of three weeks , it never missed a beat although on some remote mountain roads with *really* steep grades it would barely make walking speed .

Unless the car is trash it's worth saving and you have the skillset .

Anyone whi under stands a leak down test, will do one ~ only those who are not Mechanics of any sort will say waste of time .

jake12tech · #32 01-10-2019, 12:57 AM

Why would you perform a leak down test on a worn out engine? It’s worn out you already know it has low compression. If you have intentions of doing a rebuild maybe. It’ll tell you how good of a seal the rings are putting out. You said if it’s worn out you’d sell the car for parts. So the leak down is pointless

ykobayashi · #33 01-10-2019, 07:31 AM

Quote:

Originally Posted by jake12tech

Why would you perform a leak down test on a worn out engine? ... So the leak down is pointless

Leakdown is good for isolating problems to valve, piston clearance or head gasket leaks. Yeah, it sounds like the engine is junk, but pumping up #4 at TDC And listening at the intake, oil filler and exhaust pipe for air loss will tell you if it is something easier than a damaged cylinder.

Mike D · #34 01-10-2019, 08:03 AM

Quote:

Originally Posted by vwnate1

Anyone whi under stands a leak down test, will do one ~ only those who are not Mechanics of any sort will say waste of time .

A bit of a blanket statement there Chief don't you think?

A leak down test is a good diagnostic tool but in this case, what's it going to tell you? That you have a problem with low compression in all four cylinders? If the valves are adjusted properly you have a leakage somewhere? You are still going to have to pull the head for a physical inspection.

Whatever, it's your car, your time and your money.

Diseasel300 · #35 01-10-2019, 10:20 AM

Quote:

Originally Posted by jake12tech

Why would you perform a leak down test on a worn out engine? It’s worn out you already know it has low compression. If you have intentions of doing a rebuild maybe. It’ll tell you how good of a seal the rings are putting out. You said if it’s worn out you’d sell the car for parts. So the leak down is pointless

This is exactly my thought too. If you're only using the leakdown tester to listen for air escaping, why not just blow compressed air in the cylinder? Why bother with fancy tools you're going to use this ONE time on a pointless process? If it were only one cylinder that were wonky on an otherwise good engine, sure. On this one with oil consumption issues on a beater car with low compression in the other 3 holes? Why bother.

OM617YOTA · #36 01-10-2019, 10:20 AM

I'll +1 the leakdown test before condemning the engine. It's easy to do and yields a huge amount of info.

97 SL320 · #37 01-10-2019, 12:09 PM

Quote:

Originally Posted by jake12tech

Why would you perform a leak down test on a worn out engine?

Because a leakdown will tell you specifically what is wrong with the engine.

A mechanic won't get very far with some customers if you only tell them " the engine is junk ", they are going to ask for an explanation as to what specifically is wrong. If the tech replies with " I told you, the %$@#Q%R#$!@ engine is junk you R$##$$#Q@$. " ,that only shows one does not fully understand the system they are working on.

An engine isn't a monolithic piece of equipment that can't be repaired. If this engine has a broken valve spring, cranking compression could be low. Would you really want to scrap an engine over a valve spring or a valve lash set too tight?

What if there is a burnt valve but the bottom end is good? In this case a valve grind will get the engine going again.

I've rebuilt countless engines at a professional level and have done many of what I call " junkyard rebuilds " that result in that " good used engine " when complete. With cars this old, that good used engine is going to be increasingly difficult to find. With a JY rebuild engine quality is known and it will have good power Vs that unknown engine that may also be nearly worn out.

As for tools to perform a leak down test, all you need is a compression tester adapter with the check valve removed ( most if not all use a tire type valve with a very light spring ) and a source of about 100 PSI air. We don't care so much what % of leak down we have, we care where the air is leaking out of.

Lastly, if one is going to install a used engine, doing a leakdown would be a good idea anyway.

PS A junk yard rebuild consists of using parts on the high end / slightly over max reuse clearance. Remember, the reuse clearance assumes the engine is apart and being rebuilt. The absolute running upper limit is larger than that.

ROLLGUY · #38 01-10-2019, 01:05 PM

Quote:

Originally Posted by 97 SL320

Because a leakdown will tell you specifically what is wrong with the engine.

A mechanic won't get very far with some customers if you only tell them " the engine is junk ", they are going to ask for an explanation as to what specifically is wrong. If the tech replies with " I told you, the %$@#Q%R#$!@ engine is junk you R$##$$#Q@$. " ,that only shows one does not fully understand the system they are working on.

An engine isn't a monolithic piece of equipment that can't be repaired. If this engine has a broken valve spring, cranking compression could be low. Would you really want to scrap an engine over a valve spring or a valve lash set too tight?

What if there is a burnt valve but the bottom end is good? In this case a valve grind will get the engine going again.

I've rebuilt countless engines at a professional level and have done many of what I call " junkyard rebuilds " that result in that " good used engine " when complete. With cars this old, that good used engine is going to be increasingly difficult to find. With a JY rebuild engine quality is known and it will have good power Vs that unknown engine that may also be nearly worn out.

As for tools to perform a leak down test, all you need is a compression tester adapter with the check valve removed ( most if not all use a tire type valve with a very light spring ) and a source of about 100 PSI air. We don't care so much what % of leak down we have, we care where the air is leaking out of.

Lastly, if one is going to install a used engine, doing a leakdown would be a good idea anyway.

PS A junk yard rebuild consists of using parts on the high end / slightly over max reuse clearance. Remember, the reuse clearance assumes the engine is apart and being rebuilt. The absolute running upper limit is larger than that.

I totally agree. Even if I assume this engine needs major work (and I do), I still would like to know what is the cause of the low compression. Since three of the cylinders are 240# or lower, and I know that the valves are adjusted correctly (they were checked just before lending the car), I am assuming the valves are NOT the problem. Thinking back, I lent the car to another friend in late 2016, and he did not check the oil level then. It always burnt oil since the day I got it. I am suspecting that the rings are collapsed, and that is the problem. Either way, I need to remove the car from my insurance, and either sell it as-is, or fix it (rebuild the engine). I could even sell it to the State (Voluntary Accelerated Vehicle Retirement program) for $1,000 (what I paid for it). The problem is, the car has to run under it's own power. Also, I would like to keep this and all other classic Mercedes-Benz's on the road, and NOT scrap them.

BTW: Yesterday I pumped more MMO in the cylinders and put the glow plugs back in. I tried to start it again, with the same results. The battery was fully charged, and the engine warm from the block heaters being on for several hours. The car was sitting in the sun as well.

OM617YOTA · #39 01-10-2019, 02:59 PM

Putting around town for awhile, then a valve adjustment, then an unusual 3k of highway miles? I would adjust the valves again before doing anything.

ROLLGUY · #40 01-10-2019, 03:25 PM

Quote:

Originally Posted by OM617YOTA

Putting around town for awhile, then a valve adjustment, then an unusual 3k of highway miles? I would adjust the valves again before doing anything.

That sounds like a good plan. The cover has to come off to pull the head anyway, so I will check the clearance on all the valves before proceeding. Who knows, I may get lucky.....Rich

jake12tech · #41 01-10-2019, 09:48 PM

Quote:

Originally Posted by 97 SL320

Because a leakdown will tell you specifically what is wrong with the engine.

A mechanic won't get very far with some customers if you only tell them " the engine is junk ", they are going to ask for an explanation as to what specifically is wrong. If the tech replies with " I told you, the %$@#Q%R#$!@ engine is junk you R$##$$#Q@$. " ,that only shows one does not fully understand the system they are working on.

An engine isn't a monolithic piece of equipment that can't be repaired. If this engine has a broken valve spring, cranking compression could be low. Would you really want to scrap an engine over a valve spring or a valve lash set too tight?

What if there is a burnt valve but the bottom end is good? In this case a valve grind will get the engine going again.

I've rebuilt countless engines at a professional level and have done many of what I call " junkyard rebuilds " that result in that " good used engine " when complete. With cars this old, that good used engine is going to be increasingly difficult to find. With a JY rebuild engine quality is known and it will have good power Vs that unknown engine that may also be nearly worn out.

As for tools to perform a leak down test, all you need is a compression tester adapter with the check valve removed ( most if not all use a tire type valve with a very light spring ) and a source of about 100 PSI air. We don't care so much what % of leak down we have, we care where the air is leaking out of.

Lastly, if one is going to install a used engine, doing a leakdown would be a good idea anyway.

PS A junk yard rebuild consists of using parts on the high end / slightly over max reuse clearance. Remember, the reuse clearance assumes the engine is apart and being rebuilt. The absolute running upper limit is larger than that.

He said if it has an engine issue he’s going to sell it for parts as in the whole car. So what’s the point in wasting the time? I know exactly what a leakdown test does and tells. No point behind in it a parts car

jake12tech · #42 01-10-2019, 09:51 PM

Quote:

Originally Posted by ROLLGUY

That sounds like a good plan. The cover has to come off to pull the head anyway, so I will check the clearance on all the valves before proceeding. Who knows, I may get lucky.....Rich

Not a bad idea but I wouldn’t go further on it. Sell it for parts. If someone’s super curious of what the issue is let the next guy do a leakdown. Or blow compressed air in the cylinder like Diseasel said. Easy to pop out four glow plugs.

97 SL320 · #43 01-11-2019, 08:29 AM

Quote:

Originally Posted by jake12tech

I know exactly what a leakdown test does and tells. No point behind in it a parts car

Quote:

Originally Posted by jake12tech

Or blow compressed air in the cylinder like Diseasel said. Easy to pop out four glow plugs.

Does anyone else see the conflict in these two statements?

vwnate1 · #44 01-11-2019, 08:37 AM

"
Because a leakdown will tell you specifically what is wrong with the engine.

A mechanic won't get very far with some customers if you only tell them " the engine is junk " '

THIS I've been a journeyman mechanic for a long time and I remember peole sells me nice used cars for $50 ~ $250 because their 'mechanic' told them exactly this, no details, so I'd do the usual due diligence is diagnosis then deferred maintenance and have a good running car I could then wash & wax, sell at a serious profit .(occasionally one was *so* good I'd keep it a few years)

" A bit of a blanket statement there Chief don't you think? "

Yes, obviously so because it's a fact : if you don't understand it, you'll denigrate a thing .

As Rich says, he like me, doesn't like to break up otherwise good vehicles if there's an affordable repaid in the offing .

A valve job is a simple thing, if there's more wear / damage to the engine there's an art form to overhauling versus rebuilding, I've been doing it for fifty years and often had people who bought a used car from me tell me "! ha ! I go one over on you man, this car has a rebuilt engine and you didn't even know else you'd have asked for more !" .

Not the case at all ~ I just do a better job than the average lazy person and it shows in the finished product .

Either you know, of you don't, simple .

vwnate1 · #45 01-11-2019, 10:42 AM

Quote:

Originally Posted by 97 SL320

Does anyone else see the conflict in these two statements?

More like the similarity of those who's first response is always "no"

.