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My Compression Test - Your Verdict

Tech Talk for Rover owners.

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My Compression Test - Your Verdict

Post by GRIMACE »

Ok guys went and bought a comp tester today and spent a total of 2 hours piss fart arsing round and did a compression test on my old 3.5.

Was all fairly straight forward and here is the results for each cylinder.
1 - 129psi
2 - 131psi best
3 - 130psi
4 - 128psi
5 - 126psi worst
6 - 127psi
7 - 130psi
8 - 130psi

I didnt do a second check with a squirt of piston ring oil cause i beleive that these figures are actually quiet good (only from wat i have read).

All the spark plugs seem to be Over Rich but none where oily or damaged just slight carbon build up on each. I cleaned em and chucked em all back in.

ignore this bit its all sorted :oops: :lol:
Then lastly I may have mentioned this before but my firing order is different to the booklet, well I sat down and worked it all out today and its only one bit different...
In the booklet and online it say my firing order should be
1-8-4-3-6-5-7-2
Mine has been (ever since i got it i beleive)
1-8-6-5-4-3-7-2
so the only difference is the firing order of the two middle strokes...

I thought i would change it to wat it said in the book and see wat happens... well did that went to turn it over and got a big intake blowout :lol: scaredthe farken shit out of me :D
So quickly decided that the original order i had was the go.


Can any one elaborate on that for me and also your verdict on that compression test :)
Last edited by GRIMACE on Tue May 31, 2005 3:09 pm, edited 1 time in total.
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Post by TuffRR »

Compression is good, firing order i dont know. You sure you are counting them right?
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Post by F'n_Rover »

dont worry about the actual compression figures, worry about the variation between them. You have stuff all variation, i'd be happy to see figures like yours. i'd only worry about putting oil in the bore on low reading cylinders as a way to isolate the problem. If the reading improves, its the rings. if not its the valves. Most (non factory) manuals arnt worth a pinch of shit. I"m building a motor at the mo' . the book says to torque the rod bolt nuts to 24 foot pounds. :roll: i now use the manual to stop the desk from rocking.
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Post by Loanrangie »

Your firing order doesnt look right , sure you have it in the right order and direction ?
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Post by GRIMACE »

Loanrangie wrote:Your firing order doesnt look right , sure you have it in the right order and direction ?
tell me more about the order and the directions... all i know is thats how its goin and the current order at the moment.. and if i put it how the book asked I got a big intake blowout (lots of white smoke) didnt even bother trying to start it after i herd that :? :shock:

Also went for a wheel tyoday and the fella following me said it smelt as if I was burning oil... I get no smoke out the exhaust... the comment was (ove ther uhf) 'does your car use alot of oil'...??? it is rinnung rich I know that and i better check the oil level but I do this often and never have any issue with burning oil... will find out after i inspect it tommorow.
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Post by RobG65 »

I hope this helps....

Image

Regards
Rob
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Post by GRIMACE »

BAHAHA I AM AN IDIOT :D
I counted the cylinders from the left bank lookin at the front :oops: :D

so doin my calcs its all good :D

and the compression test cum up good :D so what to check now guys :?:
As mentioned i am getting reports from fello 4wder following me that its got a rich oil smell fron the exhaust fumes so wat do you reccomend I check next :D
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Post by Rosco (Aust) »

It may sound silly but check for other oil leaks under the car. A diff pinion leak or similar throwing oil onto your exhaust gives the same result for persons following. Look for the oily black stain on the exhaust pipe and check all the way from the exhaust manifold back. Won't take long and hopefully will find the problem. Even a havy rocker cover leak will give similar.

Compresion looks good though. :)
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Re: My Compression Test - Your Verdict

Post by Rovernaut »

AnthonyP wrote:Ok guys went and bought a comp tester today and spent a total of 2 hours piss fart arsing round and did a compression test on my old 3.5.


All the spark plugs seem to be Over Rich but none where oily or damaged just slight carbon build up on each. I cleaned em and chucked em all back in.

ignore this bit its all sorted :oops: :lol:
Then lastly I may have mentioned this before but my firing order is different to the booklet, well I sat down and worked it all out today and its only one bit different...
In the booklet and online it say my firing order should be
1-8-4-3-6-5-7-2
Mine has been (ever since i got it i beleive)
1-8-6-5-4-3-7-2
so the only difference is the firing order of the two middle strokes...

I thought i would change it to wat it said in the book and see wat happens... well did that went to turn it over and got a big intake blowout :lol: scaredthe farken shit out of me :D
So quickly decided that the original order i had was the go.

Ok, when you changed the plug leads to the correct firing order according to the specs in the manual, you would also have to change the timing again for it to run correctly.
I would put it back to manual spec. Line up the TDC marks on the pulley with the pointer and check to make sure the no 1 plug is on the number one plug hole on the dizzy. Then start the vehicle and re adjust your timing with a light.
If you just change the leads around then that could be why you got the Hmm. Also why you are carboning up the plugs as it is not firing at the optinum time with the stroke of the cylinder,
A V8 will run with slight variances, it could be that having the leads mixed up and the timing adjusted to that might disguise it. :D
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Post by GRIMACE »

thansk for the info rovernaut :)
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