PPI on 300SD
 

Hello to all,
I am going to florida tomorrow to buy a 300SD and have a particular one in mind. I had a recommended local mechanic I found on shopforum do a PPI on the vehicle today. The only thing he could find wrong was a worn drag link. He also did a Compression check on the vehicle, the readings were:
#1 = 500
#2 = 510
#3 = 480
#4 = 470
#5 = 470
He said 450 was the recommended reading and thought that the readings were high because of carbon buildup. He suggested a 1/2 quart of ATF mixed with a full tank of fuel for the drive on the way home. He said this would fix the problem.
Comments?
thanks...phal

ppi
 

what scale is he using? for psf it sounds high. the atf seems ok but im not sure it will help much.

Good compression! Just run the heck out of it on the way back. Diesels hate to idle around town load that sucker up and heat it up, all of the crap will burn and blow out.

A quart of atf couldn't hurt I tried that once and didn't notice anything. I prefer Power Service.

power service?
 

Hey HG,
Where would I find power service?
Thanks...gm

I am unsure
 

Hi Tom,
I thought all readings were in PSI, but what do I know?, not much about diesels. The mechanic didn't really seemed concerned about the high readings. The guy that owns the car is not a youngster any more and he said it was most likely from a lot of in town driving.
...gm

Autozone, comes in a big white gallon jug; $12 or $13.

Since I have been driving my SDL around town a lot lately I took it on a highway run today and lots of crap blew out. A leadfoot isn't a bad thing with one of these cars. They don't have enough power to hurt the driveline and the engines like to work.

The engine has a compression ratio of 21.5:1.

Standard atmospheric pressure is 14.5 psi.

So, it seems to me that the cylinder pressures should be about 310 psi.

The numbers that he has seem much higher than normal.

and that means what?
 

he told me that the norm was 450. Not right?

I can't say what it means.

It could be a variable caused by the test equipment or it could be high due to accumulated carbon build up.

The main thing is that the cylinders are consistent with each other and none of them are excessively low.

Thanks
 

for all the help and advice....gary

metric?
 

i thought it might be newtons per cubic centimeter or something. i know that the newton meter torque specs right next to the foot lb always is dangerous so i always mark out the nm.

310 psi = 214 newtons per cm.²

newtons per cc
 

see what i mean?... those darned newton thingies always mess me up.

Try to get a clarification from that mechanic before loosing contact or it is no longer fresh in his mind. Also if the sd is newer than 1985 use what you have to to get the excess carbon out as soon as possible if his readings prove too high in any scale. This would fit in with some of the thoughs on the 350 diesel that have been kicked around. Most likely just some initial error though. But you did pay for the compression check. hope you like the car. Plus the ppi was a really smart move as well. :) Brian I was under the impression that 310 lbs per square inch pressure would be on the pretty low side for these engines. Strange I cannot disagree with your logic though. :)

ppi
 

i dont see how it could get that high from carbon build up and run. i think the readings are wrong.