Wet sparkplugs

[Booty]

Worry about that after you have done the compression tests.

I have to take out this relay before I can do the compressio test. Othervise the injectors will pump fuel into the cylinder while testing...

 

[Booty]

Worry about that after you have done the compression tests.

I have to take out this relay before I can do the compressio test. Othervise the injectors will pump fuel into the cylinder while testing...

 

[R3k1355]

Don't forget you need to get the engine upto temperature before doing the test :up:

 

[Mr Plums]

I have to take out this relay before I can do the compressio test. Othervise the injectors will pump fuel into the cylinder while testing...

Just unclip the injectors.

 

[R3k1355]

Just unclip the injectors.

Probably do both to be honest, even with the pump off there will still be some fuel in the rail.

 

[Booty]

Just unclip the injectors.

Won’t the pump then still be supplying fuel and pressurize the system?

 

[Mr Plums]

@bloke will know best.

 

[Coops Mk1]

unplug the fuel pump from under the rear seats, provided its a not an early phase 1 car with the separate pump and sender
that'll be fine to run the test, all I've ever done and not got any erroneous readings

 

[STEVE.M]

I have to take out this relay before I can do the compressio test. Othervise the injectors will pump fuel into the cylinder while testing...

A little fuel vapour, nor engine temperature is of any concern.
Make sure the throttle body is fully open, and all the plugs are removed when you do the tests.

 

[bloke]

unplug injectors and make sure wot.

 

[Mr Plums]

unplug injectors and make sure wot.

To stop fuel entering the cylinders causing a false reading?

It was you that advised me to do so as im a bit thick

yup, throttle is off so no need to worry about that. i unplug injectors though. warm engine and crank a good few times until the needle just about stops moving.

those figures are bloody low but close so i'd be more tempted to say the low reading is down to the tester.

 

[bloke]

To stop fuel entering the cylinders causing a false reading?

It was you that advised me to do so as im a bit thick :smiley:

yup, some stuff can borewash pretty easy. not sure if the clio has a fuel cut off though on cranking and wot?

 

[Booty]

The results of the compression test are
150-150-145-155

 

[Mr Plums]

The results of the compression test are
150-150-145-155

Did you remove all the spark plugs?

Or one at a time?

 

[Booty]

Did you remove all the spark plugs?

Or one at a time?

All at once

 

[STEVE.M]

The results of the compression test are
150-150-145-155

Have you done a wet test afterwards?
The figures are fairly even, if a little low. but that may be a characteristic of the gauge.
Smear a little grease on the o ring to reduce friction when tightening the connecting hose, as I`ve noticed some don`t tighten down that well and just spin without sealing properly.
If the wet tests shoot up to 180 psi, you have a problem with the bores/rings.

 

[Booty]

Have you done a wet test afterwards?
The figures are fairly even, if a little low. but that may be a characteristic of the gauge.
Smear a little grease on the o ring to reduce friction when tightening the connecting hose, as I`ve noticed some don`t tighten down that well and just spin without sealing properly.
If the wet tests shoot up to 180 psi, you have a problem with the bores/rings.

Doing the wet test right now
Noticed that myself, I’ll try with grease, thanks

 

[STEVE.M]

Doing the wet test right now
Noticed that myself, I’ll try with grease, thanks

Repeat a dry test with the sealing grease first, in case that is the cause of the low reading, then do the wet tests.

 

[Booty]

With the grease:
160-170-165-165
With 20ml of oil:
225-225-220-220
Shouldn’t the maximum only be 180?

 

[Mr Plums]

Some odd readings here, the one that was lower is now higher on some tests.

 

[Booty]

Some odd readings here, the one that was lower is now higher on some tests.

I’m not an expert, but can’t this be because some rings are more worn that others?

 

[Mr Plums]

I’m not an expert, but can’t this be because some rings are more worn that others?

But surely the one with the lower reading would still read lower than the other no matter what test you did?

Im no expert either but isnt that just logic?

 

[Booty]

But surely the one with the lower reading would still read lower than the other no matter what test you did?

Im no expert either but isnt that just logic?

Seems right...
Well the engine wasn’t really at operating temperature for the last 2 tests, could that be a reason?

 

[Mr Plums]

Seems right...
Well the engine wasn’t really at operating temperature for the last 2 tests, could that be a reason?

Maybe, i think it has to be warm for a proper reading mate.

 

[STEVE.M]

I’m not an expert, but can’t this be because some rings are more worn that others?

This.
I still have concerns regarding the sealing of the test gauge.
From the 2nd set of dry readings I would conclude that the engine is not a basket case, though a little tired.
You have readings in the 220`s as you have 20cc of incompressible oil occupying 50cc of the combustion chamber.
Please repeat a compression test in the morning, without adding more oil.
The oil will leak past the cylinders with worn rings overnight, revealing which are worn.

On a brighter note, the valve seating is good, and I suspect the bores are good enough not to be the cause of your original concerns.

 

[Booty]

This.
I still have concerns regarding the sealing of the test gauge.
From the 2nd set of dry readings I would conclude that the engine is not a basket case, though a little tired.
You have readings in the 220`s as you have 20cc of incompressible oil occupying 50cc of the combustion chamber.
Please repeat a compression test in the morning, without adding more oil.
The oil will leak past the cylinders with worn rings overnight, revealing which are worn.

On a brighter note, the valve seating is good, and I suspect the bores are good enough not to be the cause of your original concerns.

Thanks, good to know
So the lower temperature didn’t mess up the readings?

 

[STEVE.M]

Thanks, good to know :smile:
So the lower temperature didn’t mess up the readings?

About as much difference as the current atmospheric pressure..

 

[JamesBryan]

What brand of gauge are you using?

If it's a Gunson, I would take the readings with a pinch of salt.

 

[Booty]

What brand of gauge are you using?

If it's a Gunson, I would take the readings with a pinch of salt.

The brand is Silverline.
Bought it on amazon

 

[STEVE.M]

The brand is Silverline.
Bought it on amazon

Have you retested today?

 

[Booty]

Have you retested today?

Not yet, haven’t had time today
And I’m not sure if i will be able to warm it up before the test, no space in the driveway...

 

[STEVE.M]

Not yet, haven’t had time today
And I’m not sure if i will be able to warm it up before the test, no space in the driveway...

I would not worry about warming it up.
In fact it would make any readings useless.
What we are trying to establish is which cylinders have retained the oil overnight and not leaked away.
I hope you have not started it since you did the wet test.?

 

[Booty]

I would not worry about warming it up.
In fact it would make any readings useless.
What we are trying to establish is which cylinders have retained the oil overnight and not leaked away.
I hope you have not started it since you did the wet test.?

That’s what I wasn’t sure about
Nope, hasn’t been started since the last test

 

[STEVE.M]

That’s what I wasn’t sure about
Nope, hasn’t been started since the last test

Good, if you get the chance.

 

[bloke]

with a cheap tester those results are close enough not to really worry about, if anything leakdown test but personally i've never bothered doing a wet comp test.

 

[Booty]

I did the test twice now and here are the results:
180-185-190-200
170-180-175-195

 

[STEVE.M]

I did the test twice now and here are the results:
180-185-190-200
170-180-175-195

Thanks, that`s more or less what I expected.

I think it`s safe to say that you don`t need to tear the engine down, though it`s not tip top.

These readings are left to right, gearbox end to front of the engine, as was the original photo of the plugs?

For the moment, put your old plugs back in, crank the engine over on the starter motor to expel any remaining oil.

Give the dizzy arm & cap a thorough inspection, including the carbon brush and clean up any evidence of arcing with some emery cloth.

Also measure the in line resistances of the HT leads.

I`m hoping that the valve guide seals are good.

 

[Booty]

Thanks, that`s more or less what I expected.

I think it`s safe to say that you don`t need to tear the engine down, though it`s not tip top.

These readings are left to right, gearbox end to front of the engine, as was the original photo of the plugs?

For the moment, put your old plugs back in, crank the engine over on the starter motor to expel any remaining oil.

Give the dizzy arm & cap a thorough inspection, including the carbon brush and clean up any evidence of arcing with some emery cloth.

Also measure the in line resistances of the HT leads.

I`m hoping that the valve guide seals are good.

I suspected that the engine wasn’t in top form anymore, but thanks for the confirmation that I don’t have to scrap it yet.

Yes, still the same order as in the photo.

Resistance is 2300 ohm.

 

[STEVE.M]

I suspected that the engine wasn’t in top form anymore, but thanks for the confirmation that I don’t have to scrap it yet.

Yes, still the same order as in the photo.

Resistance is 2300 ohm.

 

[STEVE.M]

Resistance is 2300 ohm.

In all 4 leads?
I suspect it all be down to injectors, but as they seem to be £90 a pop, it seemed senseless to start spending out only to find you had no compression.

I did find these though.
https://mrinjectoruk.co.uk/Bosch-0280150830-Fuel-injector-P5472325.aspx