Engine failed compression test - what next? Pug 106 Quicky

[unutterable83]

Hello all,

Trying to fix a constantly misfiring 1.4L peugeot. Any help really appreciated;

Dry PSI / Wet PSI
cylinder 1; 15/17
cylinder 2; 50/60
cylinder 3; 35/90 (but i addedd too much oil for the wet test?)
cylinder 4; 50/55

other symptoms;
cylinder 1; whitish spark plug
cylinder 2; Dead injector, black but not oily sparkplug
cylinder 3; black but not oily sparkplug,
cylinder 4; whitish spark plug

ECU fault code P0203 - fault in injector circuit - probably the dead injector
full service history
new sparks and oil
110k miles

What next? is it worth doing a leakdown test - if its rings or a valve will it be cheaper/easier to replace the whole engine?
I want the car as a track toy so i could fit a 16v, but i would liike to keep it standard if possible. THANKS

[stevieturbo]

All those readings just sound wrong.

Are you actually doing the test correctly ? and with a gauge that works ?

And if you are talking of replacing the engine, is this one even worth looking at ?

[Justin S]

with those compression readings, I would say, its worth just its weight under the bonnet...............As said, it doesnt sound quite right.

[Mr2Mike]

Did you have the throttle wide open whilst performing the compression test?

[//j17]

unutterable83 said:

Dry PSI / Wet PSI
cylinder 1; 15/17
cylinder 2; 50/60
cylinder 3; 35/90 (but i addedd too much oil for the wet test?)
cylinder 4; 50/55

Assuming you did the compression test correctly (I tend to forget to hold the throttle wide open the first time for example) then your dry tests only tell you if you have a compression issue. They should be all around the same and around 10-14BAR/145-200PSI, though that's just a guide and engines do vary - it's consistency you're looking for...and don't have. This suggests you have a compression issue in one or more cylinders - 1 and 3.

The wet test tells you if you have a piton ring issue in each cylinder. The oil acts as an additional barrier to gas escaping past the rings so if the compression goes up on the wet test you know that at least some of the gas was escaping down in to the sump and you're looking at a bottom-end rebuild.

If the oil makes no real difference you know one of two things:
1) The rings were fine and there's an issue with the valves/valve seats. They aren't sealing correctly so gas is escaping up in to the rank case and you're looking at a top-end rebuild.
2) The head gasket has blown between two cylinders and on the compression stroke in one cylinder all the gas just gets pushed in to the neighboring cylinder and quite possibly out the exhaust if it's on the exhaust stroke.

The latter is only really an option if neighboring cylinders are both low and yours aren't - it's quite a head gasket failure to create a route for gas from cylinder 1, around cylinder 2 and in to cylinder 3!

So...
Cylinders 2 and 4 look a little low but might be OK and that 50PSI is correct for your engine. They are about the same both wet/dry and between one another.

Cylinder 1 seems to have a valve issue as it's lower than 2/4 and much the same wet/dry.

Cylinder 3 seems to have a ring issue as it's much higher wet than dry.

Given the mileage I think it's just getting a bit tired in general, with the valves looking better on #3 than the others but also leaking past it's rings, #1 leaking loads past the valves and #2/3 just a bit past the valves.

[porka911t]

Where are you located ?

[unutterable83]

I followed a few guides online, including the video from 'eric the car guy' (although you have to take him a bit tongue in cheek!) - i repeated the test on each cylinder 3 times and the results were consistant.
The throttle was propped wide open.

I understand that 50psi does seem low, but assumed it was a pass - i do not have a haynes manual and cannot find the spec for the engine, its a TU3, 1.4L 8V on a W-Reg.

I am located in cardiff... anyone close?

It is a cheap 'marksman' guage, but it is brand new, and the reproducibility of results givessome validity - if the psi is incorrect, it still identifies the poor cylinders and the rise/drops in compression.

Would adding too much oil to cylinder 3 when performing the wet test provide such a high reading?

To be clear, i would prefer the car to be completly standard and just strip it for track use. I just bought an M3 Evo as a daily and bought this to repair from a friend for £180 with a view to tracking it.(I dont want to track the M3)

Really appreciate your feedback, the boys on the 106 forums would only be useful if i needed to find out which sort of neon lights and bodykits fit a 106.

I just want a fun, super cheap, lightweight track whip to get some experience in.

[Pumaracing]

Seriously, you thought 50 psi was "a pass"? Your compression tester didn't come with any instructions? I'm guessing you also never read my website.

Anyway, here.

http://www.pumaracing.co.uk/comp.htm

For any normally aspirated road engine on a CR of 9 to 10:1 the cranking pressures should be well over 160 psi. I can't even imagine how you have managed to measure 15 psi. The engine wouldn't even start with figures like that. It would be dead as a dead thing.

WTF is it with compression tests on here in the last few weeks? Can no one actually do them right?

[Old Merc]

I agree with above,it all sounds wrong?? I`ve worked on these Peugeot TU engines for years and never had one with "loss of compression" (unless someone has done something stupid to it).Seen loads leak oil from the head gasket timing cover end,external or internal.Also I have lost count the amount of injectors I`ve replaced on these engines.So assuming the engine hasn't been "Cooked dry",valve clearances are OK and nothing we dont no about? I bet there is nothing wrong with the compressions? A faulty injector has washed the pistons and bore?

[unutterable83]

Pumaracing said:

Seriously, you thought 50 psi was "a pass"? Your compression tester didn't come with any instructions? I'm guessing you also never read my website.

Anyway, here.

http://www.pumaracing.co.uk/comp.htm

For any normally aspirated road engine on a CR of 9 to 10:1 the cranking pressures should be well over 160 psi. I can't even imagine how you have managed to measure 15 psi. The engine wouldn't even start with figures like that. It would be dead as a dead thing.

WTF is it with compression tests on here in the last few weeks? Can no one actually do them right?

Wow, I attracted a keyboard warrior pretty quick, fairplay...I had missed the section on the rules of posting a new thread that forces users to pre-read a ford puma website, thanks for that nugget of knowledge


Anyway, the engine was cold so maybee that affected the readings. A dead injector or oil leak wouldnt affect compression readings would it?? I do not want to pay money to replace my dead injector if the compression is gone.

I guess I will have to take the head off and check the the gaskets/seals etc. Thanks OldMerc.

[MattYorke]

He might be a bit harsh on the keyboard sometimes, but he really knows his sh!t. And you obviously still haven't read his site, because there's no ford pumas there.

First things first, I would repeat the compression test, correctly.

Edited by MattYorke on Monday 4th July 15:50

[unutterable83]

MattYorke said:

He might be a bit harsh on the keyboard sometimes, but he really knows his sh!t. And you obviously still haven't read his site, because there's no ford pumas there.

First things first, I would repeat the compression test, correctly.

Edited by MattYorke on Monday 4th July 15:50

To be fair, it is a great site, and you are correct, it doesnt contain anything to do with Ford Pumas. My hat is off, tail between legs.

[unutterable83]

having read the puma racing site, I did follow the instructions correctly, but the engine was cold. I cant see a warm engine increasing psi 3x?
So ignoring the specific psi values of the cylinders, with 1 & 3 very low and 2 & 4 seemingly OK (i repeated the test three times cold) and the identified valve/rung issues previously identified by the dry/wet test - is it worth proceeding? I probably need to try a new guage and repeat the test i guess?

Edited by unutterable83 on Tuesday 5th July 08:20

[Steve_D]

Before you take anything apart you need to resolve those low readings.
As has been said they are just not believeable as they stand and I can't believe the engine would run if they are true.

Use a different tester and carefully followed instructions and see what you get.

Steve

[davepoth]

Atmospheric pressure is around 15 PSI. It's not a direct comparison for lots of reasons, but at 60PSI your engine is making about the same amount of compression as a Ford Model T.

If your reading is correct, your car will have somewhere around 15hp I imagine, which would make it very sluggish. Does it feel like it has 15hp?

My guess is that the camshaft has jumped out of sync a little with the crankshaft.

[unutterable83]

no it drove from london to wales at 70-80mph the whole way - i sourced some new injectors - throwing them in now... bloody thing. cheers.