May have blown the motor

[netboy]

Gave a 1983 300CD to a 18 year old for a commuter car who needed some help. The engine had a fresh tune up and usually driven 70 mph for 60 miles a day. The oil lines were less than a year old when one of the lines blew out of the swedge 30 minutes after the kid left with the car.

When I got to the car oil was all over the engine compartment and was overheating but it was not locked up, it would crank. I towed it home replaced oil lines and it overheated the next morning and shut off on me after loosing power. I replaced the thermostat thinking it was stuck. It still over heated. Thinking it might be the head gasket I borrowed a cooling system gauge that replaces the cap to see if the cylinder pressurized the cooling system. No pressure increse, but it does lack power and smokes excessively out of the breather with a loud tapping sound coming from block. What would cause excessive blowby all of the sudden?Any ideas? Could a valve adjustment fix it, is it rings or is it D.O.A.?

[04 Diesel]

Originally Posted by netboy

Gave a 1983 300CD to a 18 year old for a commuter car who needed some help. The engine had a fresh tune up and usually driven 70 mph for 60 miles a day. The oil lines were less than a year old when one of the lines blew out of the swedge 30 minutes after the kid left with the car.

When I got to the car oil was all over the engine compartment and was overheating but it was not locked up, it would crank. I towed it home replaced oil lines and it overheated the next morning and shut off on me after loosing power. I replaced the thermostat thinking it was stuck. It still over heated. Thinking it might be the head gasket I borrowed a cooling system gauge that replaces the cap to see if the cylinder pressurized the cooling system. No pressure increse, but it does lack power and smokes excessively out of the breather with a loud tapping sound coming from block. What would cause excessive blowby all of the sudden?Any ideas? Could a valve adjustment fix it, is it rings or is it D.O.A.?

Just a thought, could it be cracked head?

[netboy]

What would be the effects of a cracked head?

[Skippy]

Probably killed the rings in one or more pistons. The loud tapping is probably from a rod bearing. I'd do compression and leakdown tests before condemning the motor, but it's probably done (or up for a rebuild if you prefer to think of it that way). Running without oil will do that.

[BrassMonkey]

The loud tapping would most likely be a rod bearing - big money - the bearing is really just a thin piece of metal that protects the crank shaft journal from the piston rod. There is an oil hole right in the middle of it and oil under pressure keeps the metal from touching. The piston rod actually floats on this oil while spinning.

Run it out of oil and in very short order this float is lost and you have metal on metal. It only takes a couple seconds to burn out the bearing and cause the rod to rattle loose on the crank shaft.

If your knocking sounds like someone slamming the inside of the engine block with a hammer - this is what you have. If the knocking is a loud tick like a stuck lifter - maybe you only burned up a lobe on the cam.

In any case - its never good when an engine runs w/o oil.

The head being cracked can cause loss of compression - very hard to start and a heavy miss on 1 or more cyls.

The smoke could be coolant leaking into the cyl and being pushed out the exhaust.

Sorry for your loss

[Stretch]

Time to do a leak down test I would say:-

http://en.wikipedia.org/wiki/Leak-down_tester

You're going to need a compressor and some adapters (usually supplied in a leak down test kit) to apply low compressed air to each cylinder in turn via the glow plug holes.

Even if you can't get your hands on a tester you can still apply low pressure to each cylinder (when the valves are shut) to determine where things leak the most => exhaust pipe (exhaust valve problem), air filter (inlet valve), oil filler cap / dip stick tube (could be leaking past pistons or cracked head - remove valve cover to check).

This will help with the smoking problem...

But for the over heating problem - What is happening to the oil pressure when it gets so hot?

[layback40]

It sounds like the rings grabbed on the bore. If leak down shows bad leakage past rings, consistent with plenty of blow-by, then chances are you need to look for another motor.

[netboy]

It starts up and runs fine until it gets to 80C, then when you increase rpm is when you get the heavy smoke and loud tapping. I will watch oil pressure to see if it drops off.
I actually drove it about 4 miles to fill it up and on the way home it started losing power and died.

[barry123400]

This no oil present senario is happening enough to almost make it written in stone.

There is not one 617 engine that I can recall posted on site that really survived a no oil supply condition without major damage so far. Especially if a noise is present.

That means there is a tremendous probability yours is the same.. Although a couple of your symptoms seem odd and seldom posted if ever.

The only chance these engines have is installing a low oil pressure alarm. Still you will have to react fast if it goes off. Without one the engine is usually gone if anything occurs that either eliminates the oil supply or will not pump it.

The chances of catching the gauge pressure reading early enough are very small as you are not really expecting to see no oil pressure. The time taken to internalise this information even if spotted is perhaps too long anyways. These cars need alarms like many diesel engines already have.

I have always thought an engine shut down system was too dangerous but the best. They are best left for stationary diesel engines and train engines. Strange but one of my american gasoline cars years ago had a low oil shutoff circuit from the factory that shut the engine down.

[leathermang]

Originally Posted by barry123400

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The only chance these engines have is installing a low oil pressure alarm. Still you will have to react fast if it goes off.....

These cars need alarms like many diesel engines already have.

I have always thought an engine shut down system was too dangerous but the best. They are best left for stationary diesel engines and train engines. Strange but one of my american gasoline cars years ago had a low oil shutoff circuit from the factory that shut the engine down.

The Vega had one...
http://www.mgexperience.net/phorum/read.php?1,105913

The alarm needs to be audio...like the important warnings in aircraft...There have been some long good threads on this forum about making one..

I agree that auto shut off is dangerous.... sometimes you might need to trash the engine to get off the road and out of harms way... engines can be replaced if you are alive to do it....
It also brings up the subject of a pre oiler ( like many aircraft have).. which can be used to test the functionality of the alarm at each start up of the engine...

[Zacharias]

Someone on one of the old Mercedes mail lists once calculated the time it would take the system to pump out all the oil in a case such as this, and if memory serves it was six or eight seconds.

That being from the onset of the massive leak.... that isn't much time when you are driving, even if you happen to have your eye on the gauge at the time.

The oil lines are definitely a single point of failure. The best you can do is replace them at some interval. I believe I am currently on my third set of OEM lines.

[barry123400]

The pressure is almost inconsequental in operation. The hoses probably just rot with time and heat exposure.

Yes it was a little vega station wagon that had the low oil engine cutoff circuit. I found it by accident pulling out of my driveway. The sudden left hand turn killed the engine when the oil was a little low.

That car by the way had a notorious reputation for burning oil. Mine seemed to miss that particular difficulty and was still reasonably good when I scrapped it. The floor from the front edge of the front footwells to the hatch seemed to have dissapeared though.

I actually considered the chevette a step up from the vega back then.. To make matters worse the station wagon was the gt model. One memorial bump possibly left a headprint in the roof panel. All I remember was it really hurt and the bump in the road was not that bad.

Having an automatic engine shutoff for any reason seems like a very bad idea, a potential source of liability. I do not want my engine shutting itself off for any reason; if I need to buy a new engine, so be it.

[barry123400]

Originally Posted by Craig

Having an automatic engine shutoff for any reason seems like a very bad idea, a potential source of liability. I do not want my engine shutting itself off for any reason; if I need to buy a new engine, so be it.

I totally agree about a shut off but a low pressure audiable warning is too long overdue for installation on these older cars.

Twenty dollars and a little time just might save your engine. Otherwise the chain and sprockets plus the tensioning device on the oil pump should be scrutinized and the oil hoses to the heat exchanger changed out if they are of an unknown vintage.

You might get by with a comparison squeeze test of the oil cooler lines in comparison to a new cooler hose. Soft spots or softer overall is rot. Your engine is at risk otherwise to some extent without an audiable device.

In the last couple of weeks there would have perhaps been two engines still functioning properly if they had one. Impossible to say how the person that loaned the car might have reacted though. Any individual that installed the alarm himself would have reacted properly in my opinion though.

As for the integrety of a swaged on replacement. Screw the end into a nut welded or held in a strong vice. give it a serious gradual pull in excess of 100 pounds.

If it comes apart you do not want it in service on your car. It should be a walk in the park for any hydralic shop to do but some still seem to mess it up.