Engine Compression
 

My 7.3 engines are getting old so I did a compression check on one.

The numbers came out around 400 psi.

Is this good enough for continued work?

all 8 holes close to 400? id say your styling.:-X22

I would like to test the compression on mine, what kind of compression tester do I need?

Compression Test
 

I used a snap on gauge that reads up to 500 psi. It connects to a fitting that screws into your glow plug port.

You have to remove all 8 glow plugs. Then screw the fitting into one glow plug hole at a time. Be sure to put some anti sieze on the fitting that screws into the glow plug hole.

It is hard to reach all the glow plug holes becaue the injector lines are in the way. You may have to loose the injector lines as necessary.

Crank until the pressure stabilizes. My gauge held the pressure so I could look at it after cranking.

Mainly you are looking to see if one cylinder might be much different than the others.

I have one cylinder that concerns me more than the others. It's the number one cylinder. When I changed my injectors, it had alot more carbon build up than the others did. May be nothing, but it concerns me. The engine runs great now after the new IP and injectors so maybe I should just leave well enough alone! LOL

Compression Test
 

I have twin NA 7.3 IDI engines in my 21000lb boat. I run them at 2500 rpm all day long.

My compression test was 360,410,450,440,400,390,390,360

A coupla were a little low but these engines have 3500 hours on them. I expect them to last 5000 hours.

I have been working on the idea of adding turbo chargers to the engines and should have the project operational by next month. I will post pictures when I have it set up.

Compression
 

LSO 1123

Fly it and watch it.

Put some miles on it and then check that injector again. If it continues to carbon up then it needs to be investigated.

I think that's what I'll do. I just put the injectors in last week so I'll check it in a month or so and see if it's starting to build up.

Was that cylinder missing a copper ring at the bottom of the injector hole?

John I can't remember, I know one of them was but I can't remember if it was that one or not. One of them only came out with half of the copper washer, I don't have a clue where the other half went but it wasn't in the bore!

when I tested mine with the snapon unit they went from 420 to 510wen I get time I am going to do them again . did you testv with a warm eng or cold?

ompression
 

cold, cold,cold

I cant remember if you are suposed to do it on warn eng or not I will check the book wen I get home tomoro nite

I would not think 3500 hrs is that much time I have seen 6.534 120 hp perkins run 18000 hours under full load and a 65 kw light plant on a boat go 72000 hrs and it was not burning much oil . But I allways do short changes 150 to 200 hours on the perkins it doubled the life of eng from 9000 to 18000

When I brought my truck home I did 2 tests warm and got 380-440

I thought you were supposed to do it warm? Does warm or cold produce higher numbers?