im Axle Specialists

Technical Compression test results and spark plug appearance

Currently reading:
Technical Compression test results and spark plug appearance

E

everson38

Patron member
Joined
Jul 13, 2016
Messages
640
Points
234
Hey guys sorry if thisnis taboo as.the car ia onit a fiat but im trying to fuage the health of gf car. I just carried out a compression test on my gf SXI 2013.

I have the results but not sure of if their bad, good and also I had the spark plugs out and wanted to see if they are normal. Pictures and info attached below.

Compression test (PSI): I tested each cylinder twice so 8 in total

Dry tests:

Cylinder 1: 240 / 240
Cylinder 2: 240/240
Cylinder 3: 225 / 225
Cylinder 4: 227/ 227

Wet tests (PSI):
Cylinder 1: 300 / 300
Cylinder 2: 298 / 290
Cylinder 3: 300/ 290
Cylinder 4: 290 /290

Now here are some pics of my spark plugs and also the spark plug wells. Working from cylinder 1 - 4.

I notice spark plugs 1 & 2 were a smidge wet and also in the spark plug wells there is some slight oil residue where the spark plugs seat ( see pics) 20170716_152611.jpeg20170716_152620.jpeg20170716_152653.jpeg20170716_152723.jpeg20170716_152956.jpeg20170716_153008.jpeg20170716_153025.jpeg20170716_153100.jpeg
 
I tested each cylinder twice so 8 in total
Click to expand...


When doing a wet test you would expect to get a higher compression reading, simply because the oil has formed a seal around the piston/bore.

However, I'm not too sure about the increase that you have shown. I wouldn't have expected such an increase when compared to the dry compression test. Usually, with a healthy engine the wet compression test raises the reading by just a few psi - not the big increase that you have shown.

On the face of it, it's pointing towards worn bores or rings.

If you're getting oil in the spark plug seats that could well be a sign of a worn bore/rings - the oil is finding its way into the cylinder and when compressed, is trying to escape via the plug threads.

I'll message a guy called rallycinq and ask him to look at your thread. He seems to know a hell of a lot about this sort of thing.
 
glenn2602 said:
When doing a wet test you would expect to get a higher compression reading, simply because the oil has formed a seal around the piston/bore.

However, I'm not too sure about the increase that you have shown. I wouldn't have expected such an increase when compared to the dry compression test. Usually, with a healthy engine the wet compression test raises the reading by just a few psi - not the big increase that you have shown.

On the face of it, it's pointing towards worn bores or rings.

If you're getting oil in the spark plug seats that could well be a sign of a worn bore/rings - the oil is finding its way into the cylinder and when compressed, is trying to escape via the plug threads.

I'll message a guy called rallycinq and ask him to look at your thread. He seems to know a hell of a lot about this sort of thing.
Click to expand...
Appreciate this mate thanks for getting back to me with this
 
everson38 said:
Cylinder 1: 240 / 240
Cylinder 2: 240/240
Cylinder 3: 225 / 225
Cylinder 4: 227/ 227

Wet tests (PSI):
Cylinder 1: 300 / 300
Cylinder 2: 298 / 290
Cylinder 3: 300/ 290
Cylinder 4: 290 /290
Click to expand...

I'll preface this by admitting I don't know much about it but how about a leak in the head gasket located between cylinders 3 & 4? That would explain both cylinders reading low on the dry test and when wet the improved compression may have helped reduce the load on the leaky area?

Edit: Just googled it:

"Low compression in two adjacent cylinders typically means you have a bad head gasket."
http://www.aa1car.com/library/compression.htm

Nothing to say you can't have worn rings and a head gasket issue of course. :(
 
Last edited:
It looks fine, it's a ~5 % difference. totally acceptable.
The sparks are ok as well, there may be some oil leaking past the valve seals... but it depends ..did you try and crank it before puling them? did the car reach operating temperature the last time it was turning before doing this test?

What seems odd.. is the actual numbers; to me they are to high. I would expect around 170-190 for a healthy engine.

At this point i would just keep an eye on it.. and maybe do the test again in 4-6 months.
 
aurick86 said:
It looks fine, it's a ~5 % difference. totally acceptable.
The sparks are ok as well, there may be some oil leaking past the valve seals... but it depends ..did you try and crank it before puling them? did the car reach operating temperature the last time it was turning before doing this test?

What seems odd.. is the actual numbers; to me they are to high. I would expect around 170-190 for a healthy engine.

At this point i would just keep an eye on it.. and maybe do the test again in 4-6 months.
Click to expand...

Yeah I thought the numbers were a little high also. I think with the wet test I may have used too much oil, cz once I put the car back together and started it a lot of smoke came out the exhaust until it cleared.

1) no I did not try cranking it before pulling them. I simply just took them out of a cold engine and began the test.

2) Yes the car reaches operating temperature and all signs are fine, coolant level fine, oil is fine
 
glenn2602 said:
When doing a wet test you would expect to get a higher compression reading, simply because the oil has formed a seal around the piston/bore.

However, I'm not too sure about the increase that you have shown. I wouldn't have expected such an increase when compared to the dry compression test. Usually, with a healthy engine the wet compression test raises the reading by just a few psi - not the big increase that you have shown.

On the face of it, it's pointing towards worn bores or rings.

If you're getting oil in the spark plug seats that could well be a sign of a worn bore/rings - the oil is finding its way into the cylinder and when compressed, is trying to escape via the plug threads.

I'll message a guy called rallycinq and ask him to look at your thread. He seems to know a hell of a lot about this sort of thing.
Click to expand...
Thanks Glenn mate I appreciate that. Let me know when done pal. Thanks again
 
everson38 said:
Hey guys sorry if thisnis taboo as.the car ia onit a fiat but im trying to fuage the health of gf car. I just carried out a compression test on my gf SXI 2013.

I have the results but not sure of if their bad, good and also I had the spark plugs out and wanted to see if they are normal. Pictures and info attached below.

Compression test (PSI): I tested each cylinder twice so 8 in total

Dry tests:

Cylinder 1: 240 / 240
Cylinder 2: 240/240
Cylinder 3: 225 / 225
Cylinder 4: 227/ 227

Wet tests (PSI):
Cylinder 1: 300 / 300
Cylinder 2: 298 / 290
Cylinder 3: 300/ 290
Cylinder 4: 290 /290

Now here are some pics of my spark plugs and also the spark plug wells. Working from cylinder 1 - 4.

I notice spark plugs 1 & 2 were a smidge wet and also in the spark plug wells there is some slight oil residue where the spark plugs seat ( see pics)View attachment 182381View attachment 182382View attachment 182383View attachment 182384View attachment 182385View attachment 182386View attachment 182387View attachment 182388
Click to expand...
Hi,
If I remember correctly car has done less than 30,000 miles and
has been serviced correctly and regularly.
Your really don't need to do compression testing.
Interesting that you have given it a try for practise though, good work.
Look up how to prepare for compression testing there are some criteria to meet in order to get meaningful results and protect various engine components from damage.
Jack
 
glenn2602 said:
Why did you need to do a compression test in the first place... was there a problem with the car?
Click to expand...
Hey Glenn

Well not as such, but I belive the engine was running hot based from the hidden temp guage, but then other.than that it was fjne it wasn't losing coolant or.oil but some ppl were saying it seems high temp, others saying no it's ok etc so I was back and forth, up and down.
 
I belive the engine was running hot
Click to expand...

I don't know what a hidden temperature gauge is .. but if the temp gauge in the instrument cluster is working and isn't reading hot .. the engine isn't running too hot.

Your compression figures suggest there ISN'T anything wrong with the cylinder head or head gasket. Plus you're not using any coolant ...

If your temp gauge runs at hot - that may be a faulty thermostat or at worst, a worn water pump (the impeller vanes can wear).

If, when driving the car, the temp gauge moves up to 'hot' when idling but drops back down to normal when moving - that can be an indication of (a) a thermostat that is 'stuck' or (b) a normal engine..

You're not losing oil or coolant which suggests the engine is okay.

If the engine was worn it would burn oil. The level would go down on the dipstick and you would also smell it.

The oil in the spark plug wells may be a result of a rocker cover gasket 'weep'.

Does the electric fan kick in when the engine becomes hot?
 
glenn2602 said:
I don't know what a hidden temperature gauge is .. but if the temp gauge in the instrument cluster is working and isn't reading hot .. the engine isn't running too hot.

Your compression figures suggest there ISN'T anything wrong with the cylinder head or head gasket. Plus you're not using any coolant ...

If your temp gauge runs at hot - that may be a faulty thermostat or at worst, a worn water pump (the impeller vanes can wear).

If, when driving the car, the temp gauge moves up to 'hot' when idling but drops back down to normal when moving - that can be an indication of (a) a thermostat that is 'stuck' or (b) a normal engine..

You're not losing oil or coolant which suggests the engine is okay.

If the engine was worn it would burn oil. The level would go down on the dipstick and you would also smell it.

The oil in the spark plug wells may be a result of a rocker cover gasket 'weep'.

Does the electric fan kick in when the engine becomes hot?
Click to expand...

Hey Glenn

What a hidden temp guage is on the corsa, they don't have traditional needles on the dash, you need to do a series of button presses to get up the coolant / engine temp and it shows up as a digital number on your dash screen.

U have changed the valve cover gasket as I had an oil down wells before and it was causing a misfire so changed plugs and gasket a few month ago. (But I remember my valve cover having a distinct too tone colour to it and I believe vauxhall may have knocked over oil which may have caused this but back then I was clueless about cars. Yes the eletrical fan comes on at 109c
 
I'm here, late to the party as usual....

The dry numbers look within reason, the wets a bit high, but if you've used a lot of oil you may have caused more problems than you've solved.

What temp is it actually running at?

D
 
rallycinq said:
I'm here, late to the party as usual....

The dry numbers look within reason, the wets a bit high, but if you've used a lot of oil you may have caused more problems than you've solved.

What temp is it actually running at?

D
Click to expand...

It varies . But usually around 101 - 103
 
everson38 said:
It varies . But usually around 101 - 103
Click to expand...
I believe that is acceptable.
If the rad fan comes on and goes off that's another indication it's ok.
At what temperature does fan start ? At what temperature does fan stop?
 
jackwhoo said:
I believe that is acceptable.
If the rad fan comes on and goes off that's another indication it's ok.
At what temperature does fan start ? At what temperature does fan stop?
Click to expand...
Hey jack

The fan.come on at 109c and stops at about 105c (I think I never really stop to look proper so will check)
 
You must log in or register to reply here.

Similar threads

P
Technical Dammit - changing spark plugs and the terminal on one is broken and stuck in lead!
Replies
6
Views
194
varesecrazy
V
A
Technical TJET - Spark Plug Tip Broken - Misfire / Possibly needs a rebuild?
Replies
6
Views
853
AmixTJET
A
W
  • Question
Technical How do I remove the spark plug connectors on a 1.4 T-Jet?
Replies
2
Views
568
wieny
W
M
Technical 2006 Grande Punto glow plug issues
Replies
0
Views
344
mitchellw
M
FiatStarJet
Tuning 199A6000 and 169A3000
Replies
4
Views
352
FiatStarJet
FiatStarJet
Back
Top