Cam question

[cdkarp]

1999 Discovery I with 102,000 miles.

I have engine knock when first starting up the truck, and occasionally when at idle. The CEL light is on not sure of code, however; it always reads misfire cylinder #8. I have replaced the rocker shaft assembly with a used one.

My question is should I replace the cam and lifters? Would this help with the knock and misfire or am I looking down the wrong path?

 

[ptschram]

Gee, do you think that maybe measuring the lift might be a good idea before jumping in and replacing the cam?

 

[Chris-St Louis]

Knock, or tick? Valvetrain ticks are about twice as fast as engine RPM, Man,rod bearing nosie is at Engine RPM.

Proper diag is needed first...Dont break out the part shotgun just yet.

 

[ptschram]

part shotgun

You've still got it!:rofl:

 

[cdkarp]

Gee, do you think that maybe measuring the lift might be a good idea before jumping in and replacing the cam?

I did not think to measure the lift. What should the lift be? What is acceptable before the cam needs replaced?

Knock, or tick? Valvetrain ticks are about twice as fast as engine RPM, Man,rod bearing nosie is at Engine RPM.

Proper diag is needed first...Dont break out the part shotgun just yet.

I would be tick not a knock. Sorry about the bad description of the sound

 

[agbuckle98]

if it is bad lifters, will measuring lift height tell you anything at all? I'm not 100% up to speed on how the lifters work, but they do need to "pump up" with oil pressure correct?

 

[ptschram]

I made a tool that fits into the lifter bore and has a shaft that rides on the cam lobe. A dial indicator is positioned over the sliding shaft. This allows for direct measurement of the lobe lift.

One can also place the tip of the dial indicator at the edge of the lifter. The outside edge of the lifter is continuous with the rest of the body of the lifter.

I usually measure to look for significant variations in lift. If one lobe is more than 10-15% off the rest, it's worn.

 

[agbuckle98]

I get it, yes that way of measuring will negate any problems the lifter might be suffering from internally. Is it possible though for a lifter to just not pump up and not open the valves correctly?

 

[ptschram]

Anything is possible, just not likely. These engines eat cams like Nobody's business.

 

[cdkarp]

What cam would you recommend other than Land Rover?

 

[barefoot]

check out www.aluminumv8.com

call mark up and talk to him about his crower kit!

however, have you ruled out exhaust leaks/noise? they do tend to leak the y-pipe manifold junction. sounds just like engine noise!

what type/grade fuel you running?

like stated above...count the taps/min and get back to us! a long screwdriver works very well for a stethoscope!

my cam was worn at 145k! had a flat spot on one lobe and the corresponding lifter was mushroomed! the noise was LOUD enough to be embarrassing....more like a metallic tap tap tap.

enjoy!

 

[cdkarp]

I replace the exhaust last fall and the noise did not change after a new exhaust was installed.

I will run 93 octane gas about 80% of the time, otherwise I will use 89. I have not noticed any difference in the sound using either grade of gas. I will usually get gas at BP/Shell/Pilot.

 

[ptschram]

For the GEMS engines, D&D is the best place unless you have access to a machine shop to modify a Buick 215 cam. As they are hardened. this modification is best done with a grinder, rather than a lathe as some have suggested.

I'm glad all of my Rovers have distributors and I can buy cheap cams!