Compression test results - process and request for feedback

[ferrellmedia]

OK, I checked my compression today prior to putting the motor in.

Here is what I did.

Harbor Frieght compression tester, the more expensive one ()
No injectors in any of the cylinders, glow plugs were left in
Injector adapter didn't really seat all the way down.
Starter used for 10 seconds of rotation on each cylinder
Engine hanging on hoist, both batteries hooked up to the starter and one always on charger

And, the results on all cylinders were all EXACTLY the same, 250 - 275

So my questions are;
Did I do this wrong and my test numbers should be thrown out?
Did I do this correctly and the motor is shot?
What problems will I have if I attempt to use this engine?
Is the 250-275 acceptable?

I expected readings above 300, but didn't even get close on any of the cylinders.

Also, the cylinders all leaked down really fast, leading me to belive I wasn't gettting a PERFECT seal with this cheap ass compression tester.

The kit had a small instruction pamphlet and it said to use the glow-plug adapter, however, none of the GP adapters would fit, only the injector adapter would work. And the injector adapter tightened down until it rubbed on the valve covers, so not sure if I was getting a good seal or not. Also, the air-hose like connection from the gauge to the adapter didn't feel like it was air-tight either, really loose connection.

Thanks in advance.

 

[BigDiesel]

I would have to say you need a glow plug adapter. What do you mean by leaking down fast? If those numbers are correct then the engine may be worn out, 300 psi is the min. My compression tester is an expensive one, and it has loose feeling connection at the adapter, but still shows my engine has over 400 psi on all cylinders. Good luck.

 

[ferrellmedia]

"leak down fast" - meaning when I stop running it over, the pressure reads at 250, then after approx 1:00 it leaks down to 100 or so....

I actually expected it to peak and hold....

I bought this as a rebuild, did I get taken?

Or will it work?

 

[icanfixall]

I feel your results are from a bad tester. You really need a good compression tester. Going the cheapy way only gives you what you pay for. Try an auto parts store... Maybe they have a "real" diesel comp tester for rent.. Also check Ebay or Northern Tools for one... Whatever is going on all your cylinders seem to be the same. Hopefully its really up around 450 lbs or close...

 

[Goofyexponent]

soudn slike a valve seal, or possibly rings are gone. I do not know the history of the engine, and have had a few drinks. Could you enlighten me as to the "rebuild" specs...as to how many miles ago and was it a complete teardown, otr just a re-gasket/seal and run.

How many miles are on her now..what made you remove the engine from the truck?

I hope it's nothng serious, but you never know..could be a faulty tester!!

 

[BigDiesel]

The pressure should hold on the gauge for as long as you want it to, there should be no leak down. That may mean that one of the valve cores is leaking on the tester. Any leak any where on a tester would lower the numbers quite a bit.

 

[Goofyexponent]

Holy hell icanfixall! GET outta my head! j/k...good call, I thought the EXACT same thing as evident in our posts!

 

[icanfixall]

Goofy.... All bright minds think alike.... Welcome to my world....

 

[Goofyexponent]

Goofy.... All bright minds think alike.... Welcome to my world....

lol....and all it took was 3/4 of a quart of Alberta Premium Rye lol!

 

[typ4]

definately the tester is the problem, the tool not the person.

 

[Goofyexponent]

I like that! Tool and not the person. Can anyone suggest a good quality tester?

 

[timothyr1014]

X2 on the tester (tool) being the problem....There is way too much consistency in the combination of low pressure and 150~175 PSI bleed off in 60 seconds.

 

[towcat]

here's my suggestion. you're going to spend some money but if you don't loose the parts, this will be the last toolkit you'll ever buy.
compression tester.
http://buy1.snapon.com/products/diagnostics/mt33c.asp
adapter quick connects. YOU WILL NEED BOTH
http://buy1.snapon.com/catalog/tools.asp?tool=&Group_ID=1321&store=snapon-store
glow plug adapter
http://buy1.snapon.com/catalog/item...&group_ID=1320&store=snapon-store&dir=catalog

 

[punkmechanic]

I bought mine from cornwell tools (truck comes by work, but they are in most decent sized cities). the kit is made by star incorporated and is decent. The same kit is on the snap on truck for twice the price. I live by most of my snap on tools, but I am finding out the hard way that not all things snap on ,come from snap on (and thereby can be had for much less)

punk

 

[towcat]

I bought mine from cornwell tools (truck comes by work, but they are in most decent sized cities). the kit is made by star incorporated and is decent. The same kit is on the snap on truck for twice the price. I live by most of my snap on tools, but I am finding out the hard way that not all things snap on ,come from snap on (and thereby can be had for much less)

punk

punk-
i don't know where snap-on is sourcing the gauge from now, but my 6.9/7.3 service kit contains all genuine snap-on made stuff yes the kit is very old too.