1980 300TD buying ?s & oil preasure concerns. - PeachParts Mercedes-Benz Forum

rrorison · #1 09-07-2007, 06:17 PM

I am looking at a 1980 300TD wagon tomorrow. 178K miles non-turbo 617.

My concerns:

This car was passed over by another potential buyer because of the oil pressure. I asked the owner to start the car. At warm idle oil pressure was 1.5. I asked him to rev it to 2k rpm and he stated it read 2.5. Is this something I should be concerned with or is this normal?

I will of course check for blow-by.

I am also concerned when the owner mentioned that in the back of the car is a empty oil container by Quaker State that read 10w-40. This car belonged to his father who he said was a Mercedes enthusiast. This does not seem to be a diesel motor oil. I am hoping it was just back there to throw away and not used in the car. However if this car was run on non-diesel oil what should i look for besides blow-by?

#2 09-07-2007, 06:31 PM

Quote:

Originally Posted by rrorison

This car was passed over by another potential buyer because of the oil pressure. I asked the owner to start the car. At warm idle oil pressure was 1.5. I asked him to rev it to 2k rpm and he stated it read 2.5. Is this something I should be concerned with or is this normal?

That sounds a little strange. The idle pressure of 1.5 bars is good, but I would expect it to reach 3 bars at about 12-1400 rpm. My 617 lost oil pressure a few weeks ago (oil pump was failing) and it would not reach 3 bars until about 2500 rpm, but it was reading close to 0 at idle. I'm having trouble understanding why it would be OK at idle and too low at higher rpm.

pawoSD · #3 09-07-2007, 06:50 PM

Quote:

Originally Posted by Craig

That sounds a little strange. The idle pressure of 1.5 bars is good, but I would expect it to reach 3 bars at about 12-1400 rpm. My 617 lost oil pressure a few weeks ago (oil pump was failing) and it would not reach 3 bars until about 2500 rpm, but it was reading close to 0 at idle. I'm having trouble understanding why it would be OK at idle and too low at higher rpm.

When my 617 is warm it takes about 2000rpm to get to 3bar....but it also reads 0-.5 most of the time when warm. I have experienced no engine issues.....and I suspect it to be the oil pressure sender. Think thats what it is? Or should I be worried. I am replacing my oil pan in a month or so....so I'll be able to see how stuff looks in there...including that little intake screen. But the engine runs smooth and starts right up every time....so I wouldn't think the pump is bad. The gauge has been jittering and acting strange for quite some time. Maybe I'll just change the pressure sender tonight or tomorrow...as I am quite paranoid.

I have the new one, I was just going to wait till an oil change to do it.

rrorison · #4 09-07-2007, 07:02 PM

I am wondering if the wrong oil was used that might explain the low lower oil pressure at higher rpm.

I am really hoping this engine is ok. It has been a long hard search for one of these cars for me but I don't want to buy a money pit.

#5 09-07-2007, 08:26 PM

Wrong oil or a weak pressure relief valve would be my guess.

Palangi · #6 09-07-2007, 09:22 PM

Incorrect or defective oil filter can cause low oil pressure. Best to avoid the filters made in India.

vstech · #7 09-07-2007, 10:25 PM

I wish you good luck in finding a nice 617 powered TD, a large % of drivers swear by QS oil, the rest of us swear AT it... 10/40 oil was all you could get in the old days. qs is a good brand, I am sure it has at least CF rating, so as long as decent OCI was followed, that should not be the problem. the 123 oil pressure gauge is real, not sender, so that's not it. if it won't reach 3, as mentioned it could be a lousy filter, or it could be several other things. you may want to have the seller change the oil and filter and see where the op sits. if it was recently changed... walk away.
as a driver of a N/A TD, you may want to hold out for a turbo model anyway.
PNW is a lousy place to find them for good prices in good shape, but I am sure you will. I have 4... sorry we are so far apart... none of mine are cherry, but they were all affordable. check the Craigslists, check ebay, look around. you will find the one you want.

Hatterasguy · #8 09-07-2007, 10:32 PM

On the turbo charged cars it needs to be 3 bar by 3k rpm.

Its a very old engine, with a very old guage. As long as it hits 3 bar at 3k drive it. Put some tape over it, if it bothers you!

MTUpower · #9 09-07-2007, 10:51 PM

Quote:

Originally Posted by Hatterasguy

On the turbo charged cars it needs to be 3 bar by 3k rpm.

Its a very old engine, with a very old guage. As long as it hits 3 bar at 3k drive it. Put some tape over it, if it bothers you!

H is right. I've had a non turbo wagon- and loved it. It is not as slow as people tell you it will be, and last longer on average than the turbo model. Buy the car if the price is reasonable, and over the long run you will save money over the cost of other used cars, plus have the pride of driving a MB wagon.

tobybul · #10 09-07-2007, 11:32 PM

IMO, the more important thing is how often the oil was changed. Also, I love driving my N/A 1980 300TD. This car has lots of pep and actually feels lighter than the turbos for some reason.

178k is low for this car, IMO. If the body is in good shape and the price is right, I'd seriously consider it. Of course you gotta look at the condition of other things (vacuum, exhaust, suspension (sls?), flex discs, axle boots, tranny, etc).

MBeige · #11 09-07-2007, 11:37 PM

You're missing something here. 1980 wagons didn't have a tachometer. There was no way for him to find out if it's actually the RPM you wanted.

vstech · #12 09-07-2007, 11:53 PM

I truly love driving my 79 TD, due to it's spunky stop and go abilities. but on the highway the SD is kinda nice. I can't wait for my 85 Euro TD to get finished, so I can see how it is to drive.

tobybul · #13 09-08-2007, 12:15 AM

Quote:

Originally Posted by vstech

I truly love driving my 79 TD, due to it's spunky stop and go abilities. but on the highway the SD is kinda nice. I can't wait for my 85 Euro TD to get finished, so I can see how it is to drive.

Yup, spunky would be a good call.....another thing too with these circa is theres less stuff in the engine compartment to deal with

.

#14 09-08-2007, 10:22 AM

Quote:

Originally Posted by MBeige

You're missing something here. 1980 wagons didn't have a tachometer. There was no way for him to find out if it's actually the RPM you wanted.

Good point, if he's just guessing at the rpm it's probably OK. It sounds like the idle pressure is correct, so it's unlikely to be a real issue. It's probably easier to tell while driving it. BTW, if you do end up replacing an oil pump, the parts cost is around $5-600.