300TDI very very high compression!!!

[Matthieu]

Hi everyone,

I am from Canada (Montreal) and I am new on your forum.
I have a Defender with a 300TDI engine.
The engine have ben rebuilt last year. The head have been skim twice as far as I know, the piston ring have been changed.
After the rebuilt, the compression was between 460 and 470 on each cylinder.

Now, I did two test in the last two weeks and the compression is around 800!!

There is coolant leaking from the head.

I know I will have to open the head and check but I am wondering what you think and what could have cause the problem ?
When I took the heater plug out, there was some oil on them.
There is no pressure coming out from the hose that come from the crankcase.

Some air coming out from the oil cap but not exessive.

My turbo is leaking a bit of oil and sending it into the intercooler and then into the intake manifold. Which might bring this oil into the combustion chamber and make the compression go so high ? But I think that I would have smoke coming out from the exaust.

The other thing I am wondering is if oil could go through the valve into the combustion chamber and cause the compression to go high...

I was wondering if this could be a problem of valve or breathing system. If the breathing system is block, then, did the compression could get that hight ? And how it could be block, is it possible. I was thinking about that because when I drive for a while, when I take out the cap from the fuel tank, I hear the fuel tank poping out, like if the breathing system is block. I don't know where to look for that.

I took out the hose coming from the crank case and there is no air coming out, is it normal or should I feel some air coming out from that hose ? I took out the oil cap from the engine and there is some air but nothing exessive.

Should I do a compression test when cold and would it change something?

For now, until I open the head, can I damage the engine if I drive with that much compression ?

What do you think ?
Any idea or advice?

Thank's a lot

Matthieu

[Blknight.aus]

first up remove the injectors, pull the solenoid wire and crank the engine over to clear the pots.

then do your compression test.

if its spitting out liquid and wont stop, theres your answer.

[Matthieu]

Thank''s for you answer Dave,

What would it mean if liquid is coming out, and from where?
And do I put the injector back when I do the compression test ?
And what would be the liquid ?
And I have a weird thing going on, when I try to do the compression test, the little valve in the tester just keep breaking. I change the vale and it do the same thing again and again.

Thank's again,

Matthieu

[Blknight.aus]

which compression tester are you using?

you need to work out what the liquid is, it will be either oil or coolant.

[Matthieu]

I am using a ultrapro diesel compression tester.

Can you explain me from where the liquid would spill out and what it could meen ? And the liquid would come out when I do the compression test ? I put back the injector in ?
And some people have told me that the head that have been skim twice is good for garbage and that this is why the compression is so high.

what do you think ?

[Sitec]

Hi Matthieu.
Ok, when an engine is healthy, and a compression test is undertaken, each time the piston comes up and a reading is taken, there is a certain amount of 'blow by'... This means that some of the compressed air is escaping down the side of the piston... Giving you your lower/normal reading. If however you have an internal engine issue (which it sounds like you have) and there is oil or water getting into the cylinder, this 'liquid' helps form a seal between the piston and cylinder bore, and in turn causes a higher compression test reading......

Now, we are assuming you are doing a compression test using the starter, and not allowing the engine to run.... Secondly, if you are getting those high readings, how is it starting...? Thirdly.. You talk of liquid... If there's liquid, then there's smoke.. (You imply there is no smoke).. There also has to be fluid level loss in the sump or radiator... As you've decided to investigate by doing a compression test, and you say there is coolant coming from the head, we can reasonably safely assume that the head gasket has failed, or the head is cracked... Are there any low compression readings within the 4 tests? Has the engine ever been boiled or got hot?

My advice would be to take a step back, look closer at the symptoms, what's happening, oil colour, coolant use, coolant colour and activity (start engine from cold with radiator cap removed and watch for rapid coolant departure from header tank..), any water from the exhaust, any steam from the exhaust, any misfire, etc etc. Time spent now with a decent diagnosis will help you in the long run. Good luck, and let us know what you find. Pics and videos are good as they tell a 1000 words! :) Cheers. Simon.

[Blknight.aus]

I am using a ultrapro diesel compression tester.

Can you explain me from where the liquid would spill out and what it could meen ? And the liquid would come out when I do the compression test ? I put back the injector in ?
And some people have told me that the head that have been skim twice is good for garbage and that this is why the compression is so high.

what do you think ?

depending on the depth of the skim you can get away with a couple of shots at it BUT it wont last long if the material at the surface isnt at a certain hardness.

skimming the head does raise compression but not as much as you're experiencing.

IF you havent disabled the fuel injection when you crank the engine over you're going to be reading combustion pressure not compression. If your reading combustion pressure your going to want a gauge that can handle upwards of 2000psi. (and truth be told Id be wanting a guage that could do minimum of 5000psi)

[Matthieu]

Oh my god,
I have been doing the compression test into the heater plug!!
OK, I feel stupid now. After reading all your post I realize I was doing something wrong, I checked into the manuel and saw it!
I will do it right tomorrow and let you know.
Hopefully, everything will be better.

Thank's a lot guy,

[ozrob]

Oh my god,
I have been doing the compression test into the heater plug!!
OK, I feel stupid now. After reading all your post I realize I was doing something wrong, I checked into the manuel and saw it!
I will do it right tomorrow and let you know.
Hopefully, everything will be better.

Thank's a lot guy,

Why would doing a compression test using the hole which the glow plug be an issue????, Even if the head had a pre-combustion chamber the compression it should not be an issue.
My diesel compression tester is designed to screw into the glow plug hole.
As previous replies advised....I would start the motor and diagnose symptoms, a white sweet smelling exhaust is coolant leaking into the combustion chamber.
Are you actually loosing coolant over time? Overheating issues?

[Blknight.aus]

if he hasnt disabled the injectors as soon as it cranks on a full battery, being a tdi300, it will start.

Willing to bet that the "moisture" hes been ejecting out the glow plug holes is the injected diesel exiting combustion chamber unburnt because there was no compression on that cylinder.

Last time I did a combustion pressure check on a tdi it was pushing somewhere north of 1100psi and that was going from a hot start straight to 1500rpm

[Matthieu]

Ok, so from what I understand, I might not be doing the compression test well by not disabling the fuel injection. No matter if I plug the tester into the injector or the glow plug. By not disabling the fuel injection, that would give way to much pressure on the valve.

When I start the engine, there is a black puff, every time.
Once started, when running, iddle or driving, no smoke.
If I press the pedal to give a lot of gaz, then, some black smoke.
The engine start a little bit hard the first time in the morning when it's cold.
After the first start, it start very well the rest of the day.
When cold, before the engine get to is normal temperature, it's running not as smooth but it's very a small difference. When engine hot, it run very well.
I have good power, good acceleration. The engine is not too noisy.
No over heating issue.
The oil color is perfect as well as the coolant color.
Not white or coffee foaming in the oil cap.
No oil into the coolant.
If I open the cap of the coolant reservoir, fill it, and I give fuel, no bubble.

I am loosing a bit of coolant, leaking from the head, when the engine is running. I think the gasket might have fail.

Those are the result of my observation for diagnose of symptom.
What do you guys think ?

I am still not sure of what I do wrong with the compression test but I think I am not disabling the fuel from the injector.
I am not sure how to do this and how to do a good compression test.
I am reading the manuel right now and I am thinking about trying again, just want to be sure how to do it right and how to disable the fuel from injector.

Thank's again everybody,
I appreciate a lot all your advice and help.

[Blknight.aus]

sounds like about par for a tdi 300 that wants a little bit of maintenancy type loving.

Its not common for the tdi to leak coolant from the head gasket to the outside world, thats usually the job of the P gasket, water pump, thermostat housing gasket, the vactuator, the heater hoses, the heater hose transfer pipe and the thermostat bypass pipe fittings.

if you can confirm that it is definately leaking from the head its only a bout a days work to do an easy gasket change.

[Matthieu]

Yes, I confirm 100% that coolant is leaking from the head to the outside world.
So yes, if it's the only problem, I will be very happy.
I want to be sure that the cylinder compression is good so i want to try a good compression test. My tester only go into the heater plug.
So, can you tell me exactly how to do it ?

[Blknight.aus]

theres only 2 compression checks you can do on a diesel.

hot and cold.

before you start ensure you have a very good cranking battery thats fully charged or hook up a set of jumper cables to another vehicle that has its engine running at high idle.

for cold.

remove the wire that goes to the solenoid on the fuel injector pump, this, in theory stops all fuel flow to the injectors. As a backup crack each injector line union at the injector by about 1/2 to a full turn.

remove all your glow plugs

install your compression tester to a cylinder and crank the engine on the key. Count the number of compression cycles (I use 6-10) and read the pressure on the gauge, record it.

move the compression tester and crank the engine for the same number of compression cycles, record the pressure and then do the rest of the cylinders

The hot test is the same but you do it on a warmed up engine. it should hit the same pressures on 2-3 less compression cycles or hit about 20% more pressure on the same number of cycles as the cold test.


Something else thats worth doing while you have the glow plugs out is the leakdown test, this is done by blowing air into the cylinder through the glow plug hole with the piston at TDC on the compression/power stroke if you get air coming out the inlet your inlet valve is leaking, if it comes out the exhuast the exhaust valve leaks, excessively from the crank case ventilator and its the rings and out the cooling system and youve done a head gasket.


best of luck

[Matthieu]

Ok, that sound good. I will do all those test tomorrow and let you know what come out.

Thank's a lot Dave.

[Matthieu]

Back from the day!
So, we did the compression test like you told us.
And..... it work !!!! I have 410 to 420 in each cylinder.
what a relief!!!!
I will need to change the head gasket but that's it.
I was so happy to see the result on the the gauge.

Now, I can keep working on upgrading the truck for expedition :)

Thank you so much for all your help and a special thanks to you Dave !!!

Here a little picture of the truck!

Thank's again and I will post most picture of the process of the building of the truck from beggining soon, into another thread!

I wish you a very good day.

Cheers,

Matthieu

[Matthieu]

My Defender :)

[Jode]

Back from the day!
So, we did the compression test like you told us.
And..... it work !!!! I have 410 to 420 in each cylinder.
what a relief!!!!
I will need to change the head gasket but that's it.
I was so happy to see the result on the the gauge.

Now, I can keep working on upgrading the truck for expedition :)

Thank you so much for all your help and a special thanks to you Dave !!!

Here a little picture of the truck!

Thank's again and I will post most picture of the process of the building of the truck from beggining soon, into another thread!

I wish you a very good day.

Cheers,

Matthieu
Matthieu -
This is why I suggested that you post either here or on the landrovernet.com websites when I read your post on the SA 4X4 Community site!

I've learned that these two sites have far more technically experienced members, capable of providing accurate and helpful support!

Bon voyage!

[Matthieu]

Thank's a lot for bringing me here and the good advice :)

Merci :)

Have a great day :)

Matthieu

[Blknight.aus]

Ok, that sound good. I will do all those test tomorrow and let you know what come out.

Thank's a lot Dave.

Your welcome mate, thats what they pay me for, (well no-one here does but I spend a lot of time drunk at their expense)

you can spot me a beer and consider yourself conscripted as a tour guide when I haul the family over your way for a vacation.