2H Compression Numbers Opionions Please!

[CDN_Cruzer]

Well I did a Compression test on my 2H today it's a 1989 and the odo says 165,000Km it's a JDM unit

I am (was?) planning on doing a home brew turbo setup. I am now worried that the low compression on cylinder #2 is really bad news =[

maybe I should save my pennies and maybe some nickels and dimes for a 1HZ-T which is the engine I would like in the long run.


starting from the front

#1 - 520
#2 - 460 I added oil and got 510
#3 - 515
#4 - 525
#5 - 530
#6 - 520

So what to do? should I keep driving the truck and not turbo it?do you think the truck will last another 150,000kms with a turbo on it? The Truck runs great starts in the cold no problem. there is a little blue smoke on start up. I do not drive the truck hard I cruise about 2000rpms and I usually shift @ about 2300rpm.

 

[amaurer]

#2 isn't that low, its a little over 10% down which would still be in-spec for many engines.

Whats odd to me is that your overall numbers are so high... what is the spec for a 2H? I'm surprised that its ~100psi over a 3B...????

 

[kraher99]

2H spec is 398psi with a max deviation of 28psi....according to FSM.

 

[amaurer]

2H spec is 398psi with a max deviation of 28psi....according to FSM.

Thats more like it. The funny thing is that this isn't the first person to turn up with compression tests in the 510-530 range... whatever they're doing wrong it must be an easy mistake. Hell if I know how to read compression high, however...

 

[CDN_Cruzer]

the FSM says 398PSI or more. humm? I think I have seen over 500 from other people who have tested 2H's


Did I do the test wrong?

Here is how I did the test

Pulled glow plugs
Disconnected electrical connector to EDIC Motor
spun motor to ensure the EDIC motor did not move and the engine did not start.
hooked compression tester up to glow plug hole #1
Held throttle open
spun starter for maybe 5secs or so till the compression tester stabilized

repeated for the rest of the cylinders.

then I re-did #2 with some oil in it and got the 510 reading.

 

[lostmarbles]

Procedure seems correct but I agree that the readings are unusually high.

But the higher the better really. (We are just suspicious as to how you can achieve such good figures when we can't )

 

[amaurer]

(We are just suspicious as to how you can achieve such good figures when we can't )

x2. nothing a bag of sand can't fix......

 

[crushers]

turbo it and drive it.
then when you have the time and the willpower tear into...

i wouldn't let that stop me...

 

[Tapage]

turbo it and drive it..

X2 you will be surprised on how hard can run and much reliable can be your 2H with a turbo on it ..

 

[crushers]

could be a stuck ring...

 

[Radd Cruisers]

Pull the plugs, Seafoam the cylinders overnight, spin it over to get the stuff out of the cylinders, stick the plugs back in and call it good...

Had a guy from Kamloops call me before Christmas wanting to rebuild his low mileage 2H because it smoked very badly - I told him to Seafoam soak it for 2 days - he called back about a week later and it was good as gold (and I lost the sale on a good 2H as a result).

~John

 

[crushers]

honesty is never a lost sale...

 

[CDN_Cruzer]

OK Sounds good I will seafoam it today and see how it goes! thanks for the info! I hope all is well!!!

A stuck ring? what does this mean? could you expand on that a little?

 

[Radd Cruisers]

OK Sounds good I will seafoam it today and see how it goes! thanks for the info! I hope all is well!!!

A stuck ring? what does this mean? could you expand on that a little?

The rings fit into the cylinders and have a slight springy-ness to them to maintain a seal between the piston and cylinder wall. If they get over heated (badly), coked up with carbon, or glued in place with oil sludge, they are unable to maintain their tension against the cylinder walls. Once the seal is no longer good, oil can leak past (smoking) from the crankcase, or combustion gases can blow by into the crankcase (loss of compression, excessive blow by).

If the rings are carboned-up or stuck into place, then using a solvent to loosen the sludge/carbon can allow the rings to resume their normal task of sealing the pistons to the cylinder walls.

This process doesn't always work, but is certainly cheaper than tear-down and is worth trying.


~John

 

[crushers]

decent description...

 

[CDN_Cruzer]

Thanks for the description!

I filled the cylinders with sea-foam today and I will let it sit for a few days.

The other thing is when it's below 0 degrees Celsius when I start the truck it idles rough unless I give it some gas almost like one cylinder is not catching then it smooths out I have put all new glow plugs in and the problem continued.

also my oil pressure stays a little higher than normal till the truck is warmed up.

 

[crushers]

with one low cylinder thsi is a definate possibility.

 

[Radd Cruisers]

The other thing is when it's below 0 degrees Celsius when I start the truck it idles rough unless I give it some gas almost like one cylinder is not catching then it smooths out I have put all new glow plugs in and the problem continued.

also my oil pressure stays a little higher than normal till the truck is warmed up.

On a cold start the idle should be bumped up with the hand throttle so that it runs smoothly...

The oil pressure is always low at a hot idle - this is normal. Install a good quality oil pressure gauge, preferably one with a low oil pressure light that can be calibrated to come on at about 5 or 6 PSI.


~John

 

[Tapage]

I feel scary if I see my oil press under 16 - 18 PSI @ hot idle ..

 

[CDN_Cruzer]

I got home from work this morning and spun the motor to clear the sea foam out it makes a great show as each cylinder POUFFFS out all the sea foam!

did that till I felt enough was out and my batteries still might have a chance of starting the truck!

Put the glow plugs back in and installed a new oil line for the vacuum pump as the old one was leaking.

Truck started right up and started smoking a lot! and was pukin out some like black sooty goo.

I went for a drive and it smoked a lot A serious smoke screen! went onto the highway and it stopped smoking after about 10mins. I drove for about 45mins to get her nice and hot and charge up the batteries


seemed to be running a little stronger it was idling smoother.

Thanks for all the help!