QuestionI own a 96 discovery4.0 engines runs like it has a misfire. its good in spark,the spark plug on both cylinders smell like gas.
I compression tested each cylinder, 2 cylinders on driver side of the head next
to each other compress at 30 and 40 psi all others are at 155psi +/- no smoke out
the pipe, i hear a valve tap like that gets louder when giving it RPMs loss of
power at same time, i would have to accelerate slowly, and i feel preassure and
see grayish smoke when i pull the hose that serves as a pcv valve(heater hose from
top of valve cove to intake assembly) would bad valve seals on those to cylinders
cause the compression to drop so low?
Answer******************Follow up************************
Hi Milton,
did you ever get those manifold bolts off?
JohnMc
***************************************************
Hi Milton,
thanks for the comments. Whenever you have a problem with socket sizing using mm, switch over to inches. I've found on the exhaust that some bolts are metric and some are imperial. Now that I do most of my own work, I try to keep it metric. It does not surprise me that you find mixed bolts on your Disco.
I use a Haynes manual to do most of my work and it almost never lists the actual bolt size. You can try the following website and see if they have more specific data:
www.discoweb.org
They have an excellent tech section and you can start looking there. Someone mentioned that the size was 3/8-16 x 1".
Regards,
JohnMc
*********************************************
Hi Milton,
yes, you probably have problems with the exhaust valves. Its common with Series I Disco's and 4.0 engines. The only cure is a valve job...might as well do all of them and be worry free for the next 100,000.
Best of luck,
JohnMc
