Anyone got a short synopsis of a compression test for a 300D, ( i have the guage)
 

I know it sounds duh and intuitive and easy to do..When you think you know everything you always get cocky and screw up. Can someone give me a brief summary, most importantly things NOT TO DO...

Don't
 

My list of don'ts:
Don't leave the fuel lines in place unless you want your gauge to suck diesel. Cover the IP with a cloth to absorb any diesel ejected during the tests.
Don't forget to unplug the glow plugs
Don't test through the injector holes unless you have replacement rings to put them back in. I use the GP holes
Don't turn it over unneccessarily long. About 6 revolutions usually does it.
Don't think this is the end all test. Retest if you think you need to.
I know there's more but this is a start.

Good list.

Actually the injector seals are iron and reusable. I've even seen these engines without them in place at all and they ran fine. I would not run without them mind you, but I saw one that was seeping a little fuel by the injectors and it turned out that there were none in there.

Good luck,

thats correct
 

..and now I know where the leaks I could never get rid of were, I was missing these rings...

The heat shields cannot be reused and must be replaced even if you have fitted a new one 5 mins earlier. The heat shields are made of soft steel, EN8, and collapse when fitted sealing at the injector body and on the face of the nozzle preventing hot gasses from surrounding and overheating it. Failure to fit new ones will lead to premature deterioration of the nozzle needle seating.

Mine seemed OK after a few reuses. There is a way to bend them back a little to provide a good sealing surface afterward.
All this said, your results may vary. I am by no means trying to say that this is better than going out and buying new ones. I don't think that they're that expensive. I'm actually going to go out and buy a new set myself now.

I noticed that there is a 7mm and 10 mm size listed for my car. Which ones should I get. I don't remember what size my old ones are and I don't want to pull one out just to see what size it is.

Hold shut off switch while cranking...
 

A good tip I saw on the www.repairlix.com video was to push the emergency shut off switch while cranking.

By the way, does anyone know of a source for a reasonably priced 400 lb gauge (under $100)?

If you like, I will write a summary of his procedure.

PS... let us know what your readings were.

PS... it's also reccomended to have your valves adjusted before doing the test for most reliable results... you can lose a lot of pressure through poorly adjusted valves.

DJ
The soft shield with the 10mm hole (Pt No. 64760331) superseded all earlier shields with smaller holes about 15 years ago. It was found that the smaller holes (7mm and 5mm) did not consistently sit squarely on the nozzle face and would leak. The seating on the PC is actually spherical, as is the chamfer on the shield.
Yes, you could hit it with a ball bearing and bend it back but I have seen far too many injectors packed inside with carbon and corrosion to recommend you do this to save 5 bucks perhaps once in 5 years.

And don't forget the most important step in the whole process...Scratching your...head trying to figure out what to do with the numbers. Are your numbers correct? Should you do them again...and again? What are "good numbers"? What should I do if one (or two) is a little low? By low I mean a 10% deviation for the average? Or do I mean 10% less than the next lowest one? Or should the spread be only so many %?

Cut to the chase and loosen the injector line at each cylinder one at a time to see if you can find the "dead" cylinder. Then swap that injector with one from a good working cylinder and see if the problem follows the injector, or the cylinder.

No need for a diesel compression gauge or parts, unless you consider the heat shields mentioned above.

240Joe

diesel compression check sale
 

These were just on sale at Harbor Freight for $79 a few days ago. I get sale emails from them so I dont know if it was an online sale only or if it included the stores.