How to perform a compression test...

[sternal]

...step by step !

Following on from my speed thread its apparent the van needs to have a compression test.

Looking on flea bay I can purchase one for £15

I have looked at a few sites of how to do a compression test it looks fairly easy

To me the hardest part looks like taking the spark plugs out (pain to get in !)

Or is this something my mechanic should do (next week) as I am away this weekend in the GL54 area (if anyone is round that area and feels kind enough to offer to do the test for me then that'd be great !)

Many thanks in advance

[DuaneEddy]

This is going to end in tears!
MY OPINION - Please take the vehicle to someone reputable and put your hand in your pocket and pay.
FACTS - You doubt your own mechanics ability - Otherwise you wouldn't be on the forum belly aching - You have had the offer of a repair on the previous post BUT still express a desire to take the vehicle to an unknown person in the GL54 Area - You wish to spend £15.00 on an unknown / cheap tester when they are available at probably every Auto Parts Retailer in te country and then express with a sad face that it looks a pain to get into!!
Good Luck

[sternal]

This is going to end in tears!
MY OPINION - Please take the vehicle to someone reputable and put your hand in your pocket and pay.
FACTS - You doubt your own mechanics ability - Otherwise you wouldn't be on the forum belly aching - You have had the offer of a repair on the previous post BUT still express a desire to take the vehicle to an unknown person in the GL54 Area - You wish to spend £15.00 on an unknown / cheap tester when they are available at probably every Auto Parts Retailer in te country and then express with a sad face that it looks a pain to get into!!
Good Luck

Bit rude mate !

I don't doubt my mechanics ability at all ! Yesterday I was told on this forum to try and do things on my own give it ago I think was mentioned !
And no not an unknown in GL54 area simply if one of you kind people are around (a few of you seem to know a lot)

Forums are supposed to be nice places not to get abused I get that at work !

[weldore]

With a little guidance from this forum most jobs can be diy ...IMHO

[R0B]

Belly aching.What are you on about.The guy is asking for help.In case you had not noticed,that is what the forum is for.

Otherwise you wouldn't be on the forum belly aching

[DuaneEddy]

Guy's /Gals
Ok - I apologise
I realise the forum is for help and seriously - I am trying to help - Tact may not be my strong point!
The post should have read "belly aching about the mechanic" -
My advice to follow on - Please ensure that the spark plugs are not siezed in the heads and that you have sufficient tooling prior to going to GL54 and allowing unknown quantity to check your van
I realise that most jobs are "Do able" and I respect that you are sensible to search on the internet for advice (watch you tube video's) on the subject etc
I also understand that we all start off as "Babes In Arms" and that we can achieve most things given assistance / training.
Its just that I also see - the hazards and implications that can and do occurr when events are set in motion.
Sorry - If my opinion sounded Rude - It was an honest opinion and the start line say's "It will end in Tears"

[sternal]

Spark plugs not seized I only put them in yesterday.

Group hug

[DuaneEddy]

OK - here we go
Go down the shop and buy a compresion tester -
The rest should tally with your research
Remove spark plugs - Ensure engine will not start by removing coil lead Low Tension lead - Place tester in first hole (your choice - ) - Hold throttle in full open position - Crank engine on starter for around 10 revolutions - record results.
The majority of testers have a one way valve that holds the pressure So you can do this job yourself.
Repeat on all 4 cylinders - Compare results - Should be whithin around 10% of each other - normal engines run around 8 to 1 compression ratio So expected readings are in the order of 120-170 PSI
Test again hot if required - Be Careful not to burn yourself on hot items
If any readings are different - Acheck is made by squirting a drop of engine oil in the bore - If the pressure rises - problem is normally piston ring related - If pressure stays reduced - Indicative of a burnt valve
If Two are low and are adjoining - Indicative of failed head gasket - (NOT the case on the water boxer as they use a copper ring instead of a conventional gasket
Please report findings and again Good Luck

[itchyfeet]

^^^ you really need to test with a hot engine, cold readings are not really important.

[DuaneEddy]

^^^^^^^
Above Correct

The thing is - If the engine is not running and you are fault finding - you have no choice BUT to do cold

In addition it is safer to carry out the procedure cold initially

This test only gives an indication of Bore - Piston - Rings - Etc - A lot of engine manufacturesrs will carry out a "blow by test" and infact I have seen Thermal imaging Camera's being used and cameras on a flexi stick - BUT we digress!!

[itchyfeet]

it's unlikely that one cylinder being low would prevent the engine from running so unless thay are all low and the engine is totally shot it should run and get hot so no reason to do it cold IMO.

[DuaneEddy]

Unless its a two cylinder engine - Which has no bearing on this case your honor!
If the engine compressions are correct (in the green zone) when cold and the pressure drops off on one cylinder - it could be as simple as a tight tappet.
The effect would be the same as a lot of single cylinder diesels that rely on a decompressor to allow the operator to get a good swing

[shepster]

Mate of mine recently had a comp test on the same engine as you have and all cylinders were around 150 so this is what you're looking for.

[sternal]

Cheers for all your help
Im away for a few days, so may try it when I get back or watch my mechanic !

[edoh]

alternatively...............
https://club8090.co.uk/wiki/Te ... on_testing" onclick="window.open(this.href);return false;