Arghhhh, bad compression, is my patrol doomed?

Submitted: Friday, Aug 10, 2007 at 17:53

ThreadID: 48593 Views:3064 Replies:4 FollowUps:5

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justin71

Hi

I posted on here a few weeks back, excited to modify my patrol etc. and we've been moving house the last 2 weeks and the car has been losing power over that time.
When my wife towed the horse float yesterday with no horse she couldnt get past 40km an hour on a hill (on gas). SO I had it looked at today and spark plugs, leads, fuel filter are all SHOT. And compression test showed 100PSI, when it should be around 170 PSI. So I am bummed big time right now as it could be thousands for new rings or valves.
I had the car tested by STATE ROADS and they stated they do compression testing, and on the test the guy just put a tick and said OK, no PSI rating there. So I have sent him an email to ask if he actually did a compression test or not.

Also the mechanic stated we should have overdrive OFF during all towing (which I knew) and also all town driving, except on highways, is this right?

One other thing, not sure what the little power switch beside the auto shifter does on the patrol , it doesnt seem to change JACK when I click it, any ideas?

Sorry if I appear like some NOOB who knows nothing but u know, if it looks like a duck and sounds like a duck......

SO we decided we would get the mechanic to do the plugs, leads and fuel filter and see if it has much more power.

I'm basically clueless and looking for advice from the mechanically minded on here, should I sell it, fix it, get a new motor?

Its a 99 4.5 litre patrol with an impco gas conversion on it. I was under the impression that Patrol motors were BULLETPROOF, the mechanic indicated that there hsould be no compression problems til 300k kms, but maybe we were conned or it was just bad luck???

hope someone can shed some light on my dark afternoon!

regards

Justin
Geelong

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Reply By: ross - Friday, Aug 10, 2007 at 18:06

Friday, Aug 10, 2007 at 18:06

First thing to do would be to find out if its the rings or the valves.
If its valves it would be lot cheaper.

You didnt say how many Kklms its done but I take it a lot less than 300000klm.

Its one of the pitfalls when you buy a used vehicle,you never know exactly how the PO treated the vehicle.
They could have gone 40000 klms without an oil change,do that once or twice and it certainly brings down the longevity of the engine.

Is the compression down equally across all cylinders?

If it needs rebuilding,a full rebuild is the only way to go if you want to keep the vehicle.

AnswerID: 256749

Follow Up By: justin71 - Friday, Aug 10, 2007 at 19:11

Friday, Aug 10, 2007 at 19:11

Hi Ross, thanks for the reply!

Ive since spoken to the guy that did the inspection. He did a compression test but it wasnt the one wher they take the spark plugs out, it was the one where they balance test the cylinders and take the distributor cap off. He said there was no abnormalities with the compression test and the balance checked out fine. He said he would have been more happy if my compression test had been in the 140 range for a hot engine, but said he wouldnt do anything as its done 180k ks and its not a new vehicle. It drives well, but when the wife tried to pull an empty doule horse float yesterday on gas it was going 40ks up hill flat stick, but I think she should have put it on gas and taken overdrive OFF. So I will get the mechanic to put new plugs, leads, fuel filter and see how it fares. Hopefuly I was just pannicking unneedingly. I will get the mechanic to do the compression test on each cylinder to see if its even. I did see the log books, its had regular services but missing the services for one or two in the last few years, thats all, not too bad.

To find out if its the rings or valves it would require a lot of work just to assess the situation wouldnt it? Like how much do you think $$$ wise? I was thinking of just seeing how it gos with the service.

regards

Justin

Justin

FollowupID: 517842

Reply By: Shaker - Friday, Aug 10, 2007 at 19:09

Friday, Aug 10, 2007 at 19:09

You really need to do wet & dry compression tests to ascertain whether it's rings or maybe just needs a valve job, which could well be the case as it's on gas.

I think the little switch beside the shift just adjusts the auto shift pattern.

AnswerID: 256758

Follow Up By: justin71 - Friday, Aug 10, 2007 at 19:12

Friday, Aug 10, 2007 at 19:12

Hi Shaker

It registered as 115PSI HOT, and 100PSI cold on one cylinder, havent got him to do the rest, but I think I will seeing as hes already pulled the bugger to bits!

FollowupID: 517844

Follow Up By: justin71 - Friday, Aug 10, 2007 at 19:13

Friday, Aug 10, 2007 at 19:13

Oh, its only had the gas conversion in June of this year and is an IMPCO one, so I was thinking that the valves should be ok.

FollowupID: 517845

Follow Up By: Shaker - Friday, Aug 10, 2007 at 19:22

Friday, Aug 10, 2007 at 19:22

All you have to do is a comp test, then squirt a little oil into each cylinder & test again, if the comp goes up then it's rings.

FollowupID: 517846

Reply By: Member - Davoe (Nullagine) - Friday, Aug 10, 2007 at 20:45

Friday, Aug 10, 2007 at 20:45

My memory could be bad but I thought around 100psi was normal for a vehicle running on unleaded fuel?

AnswerID: 256768

Reply By: Andrew-rodeo - Friday, Aug 10, 2007 at 21:56

Friday, Aug 10, 2007 at 21:56

Have you checked the tappets? Is the same lack of power on gas and petrol?

AnswerID: 256773

Follow Up By: justin71 - Friday, Aug 10, 2007 at 22:17

Friday, Aug 10, 2007 at 22:17

Well that was the other thing, the mechanic said there was some noise from the tappets. I notice more power of petrol than gas which is normal I guess, but I wouldnt know what was abnormal for a patrol as I havent had one for long, but it has seemed to decrease in power the last couple of weeks, but I am hopipng the new plugs and leads and fuel filter might help a bit.

FollowupID: 517866