Diagnostic results???

[lorenambrose]

Here are the results of the mechanical diag done today.

2003 Ranger 3.0l flex. 54000 miles.

Idle vacuum 18in.

Compression

cyl1 161
cyl2 156
cyl3 160
cyl4 160
cyl5 146
cyl6 165



Should I be concerned with any of these numbers?

 

[Original_Ranger84]

Cylinder 5 looks a tad low but nothing i would be concerned about unless its running really bad or something.

 

[BRUTUS_T_HOG]

what is the problem you are having? try re-testing the compression to see if cyl 5 shows low again

 

[Original_Ranger84]

I don't think its low... If i remember anywhere between 145 -160 is normal for a gas engine at 8:1 or 9:1 or whatever.

 

[BRUTUS_T_HOG]

yeah its not low... but it is different so it could cause a power imbalance

 

[Original_Ranger84]

lol i don't know if he even has a problem, probably just a routine check up.

 

[Rearanger]

Here are the results of the mechanical diag done today.

Was the engine hot when you did compression? Vacuum is on low side of accepted range (17-21). Was needle stable? Here are my compression numbers at 11,348 mi for comparisons - engine hot.

1. 190
2. 190
3. 185
4. 185
5. 192
6. 185

Should I be concerned with any of these numbers?

Without some base numbers at a lower mileage it's hard to draw a conclusion. What are you going to do if you have concerns - sell the truck, rebuild the engine? If you're not having running problems then I would not have concerns - but I would be a little disappointed with these numbers at 54k mi.

 

[lorenambrose]

This truck experienced a catastrophic overheat and dumped all coolant at once. I ran until it cut off and died. The dealership sent the heads to a machine shop to be checked and machined and replaced the head gaskets. I dont think it has run quite right since. I could be slightly paranoid though. I is back in the shop for a few other warranty items and instead of a power balance check I insisted on a mechanical compression, vacuum and cylinder leak down check. All passed but the numbers look low. on the one cylinder and the vacuum in on the bottom end of the acceptable range. They did that any psi loss in the cylinder was through the crankcase, which means rings. However I do know there is always some loss as the cylinder is not air tight.

 

[Rearanger]

They did that any psi loss in the cylinder was through the crankcase, which means rings.

For good leak down test piston should be held in TDCC position, engine hot of course. There will always be some leak past the rings, especially at the ring gap, and maybe through valve seats. Did they tell you the actual leak rate in each cylinder? I did a leak down on another truck I own a couple of years ago. It had about 135K miles on it and I was replacing valve seals at the time. Engine was cold and pistons in BDC but I still managed only a 5% leak rate in all cylinders.

 

[lorenambrose]

I remember them saying it passed a 5% leak down test.

 

[Rearanger]

Since it still seems you have warranty I can't say they aren't trying to get out of doing the needed repairs. Independant shop to test might not hurt, but with the numbers so far you'd have a tough time getting them to rebuild the engine for better numbers. Read the fine print of the warranty.

 

[Original_Ranger84]

If it runs fine now i wouldn't rebuild the engine... that a serious cost and if the engine blows then the dealership is still under warrenty to fix or replace it provided you have a warrenty or it hasn't expired. i would highly doubt they would skip out on somehting it needed if there was even a slight chance it would lead the the engine blowing becasue a blown engine cost them alot too.