low compression

joeyfast13 · Post by **joeyfast13** » Fri Mar 04, 2011 6:12 pm

i have recently took my motor out and put all new gaskets on..
and now my compression reads 30 psi on one cylinder one and the rest lower the motor ran great before i pulled it
any ideas?

this is a f134 i checked the intake valves and adjusted them

Cacti_Ken · Post by **Cacti_Ken** » Fri Mar 04, 2011 7:29 pm

So you had the motor out and just replaced gaskets and thats it?

DJ · Post by DJ » Fri Mar 04, 2011 8:15 pm

Did you check compression before you took it out?

joeyfast13 · Post by **joeyfast13** » Sun Mar 06, 2011 1:02 am

i took the motor out and replaced all gaskets and painted it and put in a new clutch

the compression was 90 before i pulled it

Post by **wesk** » Sun Mar 06, 2011 10:40 am

Can you give us a list of what gaskets you changed, what parts you removed and reinstalled on the engine and what adjustments you made on the engine?

joeyfast13 · Post by **joeyfast13** » Sun Mar 06, 2011 11:06 pm

i got a full fel pro gasket kit i didnt replace my rear main i just put the oil pan, timing cover, front plate both sides both valve cover gaskets carb gasket, head gasket, exhaust manifold gasket, water pump, pretty much everything..

i had to remove the cam gears but i did line the dots back up
i have adjusted the intake valves because they had play its acting like the valves arent closing cause the compression is just to low like the valves are open on the compression stroke

Post by **wesk** » Sun Mar 06, 2011 11:14 pm

Try doing a leak down test on it. That will pinpoint where the leak is. If you have never done a leak down test check here:
http://www.carcraft.com/techarticles/11 ... index.html
http://www.wcengineering.com/articles/leakdown.html

Did you set the valves at .014 or .016 gap? Did you set them cold or hot?

joeyfast13 · Post by **joeyfast13** » Sun Mar 06, 2011 11:20 pm

Well i dont have a leak down tester

Post by **wesk** » Mon Mar 07, 2011 12:04 am

They are simple to make. The simplist is an air pressure regulator w/gage, a quick coupling, a hose adapter from a compression tester for the spark plug hole.
http://www.650motorcycles.com/LeakDownTester.html
http://www.top-fuel-racing.com/leak.asp

Bring each cylinder up on compression then apply 10 pounds of air to push the piston to bottom center and raise the pressure to about 50 pounds.

Listen and look for the air leak source:

Carb for intake valve leaks
Exhaust pipe for exhaust valve leaks
Bubbles in the radiator for water jacket and head gasket leaks
Dipstick tube for bad ring leaks
around the edge of the head gasket for external gasket leaks.
the other spark plug holes for leaks between cylinders

What gap setting did you use for your valves?

joeyfast13 · Post by **joeyfast13** » Thu Mar 10, 2011 10:24 pm

I just took the slack out i haven't set it to specs
I lined the dots up on the gears is there more than one way

Post by **wesk** » Thu Mar 10, 2011 11:18 pm

The jeep 4 banger has solid lifters. They must have the correct running clearance or one of two things will happen to each valve. If set too loose it will stay closed too long and the exhaust valves will get too hot and burn. If set too tight the valves will not always close fully and leak. You only remove lash (" just took the slack out ") on engines with hydraulic lifters.

Are you referencing the correct engine serive manual for your engine? If not the correct one is available to you free to download in PDF on our downloads page.

joeyfast13 · Post by **joeyfast13** » Sat Mar 12, 2011 2:10 am

But if i lined the dot up on the gears is there a wrong way to do it

Post by **wesk** » Sat Mar 12, 2011 2:44 am

Lining the dot up on the gears only sets the cam gear in time with the crank gear.

this is a f134 i checked the intake valves and adjusted them

The issue is the valve clearance adjustment. That adjustment for the exhaust valves is between the valve stem and the cam follower and is set to 0.016". The intake valve clearance is set between the valve stem and the rocker arm at 0.018. If you have any of these adjusted as you said above

I just took the slack out i haven't set it to specs

then they are too tight and will not fully close.

joeyfast13 · Post by **joeyfast13** » Sat Mar 12, 2011 4:55 pm

Well thats what i think it is when number 1 comes up one its compression stroke maybe the cam is off and opening the valves...

But i will adjust the valves to spec and ill post back

Post by **wesk** » Sat Mar 12, 2011 5:22 pm

If you used the manual and set gear marks correctly then when #1 is TDC on compression both valves will be closed unless they are adjusted too tight.