Carbon Cutting Exhaust Valves?

[syugg]

It?s my understanding some of the 1996 and newer Disco?s had issues with sticky exhaust valves which can cause momentary loss of power/engine stagger. The sticky valves results from carbon build up on the exhaust valve (see link to article below for details).

http://robisonservice.com/servicedep/pdfs/carbon_fouling1.pdf

At some point, I?ll be taking the heads off my 1996 D1 to replace the head gasket and perform a complete valve job. If I have the older style exhaust valves, I will be installing the carbon cutting exhaust valves.

Anybody know which year or particular VIN #?s when Land Rover began fitting the Discos with the ?newer? style carbon cutting exhaust valves (see pics of the older and newer valves)? I want to order the necessary parts before I start taking the engine apart.

 

[barefoot]

don't know the date but it was 97 when they put the "carbon buster" valves in. basically they put a 360 degree notch around the stem and i don't think it did much to fix the problem

the carbon problems on these things are because the valve train had to be "tweaked" in order to pass us emissions. overseas models apparently don't have this problem.

drive it like you stole it (get the rpm's up frequently) and run high octane gas and you should be ok.

my 96 has 159k and has not had a valve job...runs fine.

are you taking it apart solely for the purpose of switching out the valves?

enjoy!

 

[syugg]

I haven't had any problems with my 96 D1; however, since I will be elbow deep in grease to replace the head gasket, I was thinking about changing the exhaust valves to the updated carbon cutting exhaust valves. The genuine valves are pricey. In any case it sounds like from your assessment, that it makes very little or no difference.

 

[d1driver]

Same blocks, heads, etc. There obviously was a reason to change to the new valves. If it were only a very minor difference, why would LR go ahead and change them? I am sure the carbon cutters cost more.

 

[Ppaulred96]

Landrover has an oversized ream tool for the sticking exhaust valve issue. If the valve is in good shape you can go through a simple 3 step process once the head is off the truck. The process basically reams or enlarges the exhaust valve guide to prevent sticking. If the valve is damaged Landrover recomends the new style valve. You do the same process with the intake but you do not use the last step to enlarge the guide. I do not have the tool number on this tool but just complete my set of heads on my 96. I was able to reuse all my exhaust valves. There should be a Landrover bulitin on this floating somewhere - I have the hard copy but nothing I can e-mail.

 

[rover4x4]

WHats the cause, short trips around town with cheap fuel and lack of maintenance?

 

[JohnB]

My machinest told me they just made the valve stem shorter so the carbon doesn't get up into the stem.

 

[Ppaulred96]

the photo I saw of the improved exahust valve had a small groove (maybe 1/4") cut into the valve stem. 96 trucks were the worst for carbon build-up. Yes short trips, letting the truck idle for longer periods of time & low quality fuel all add to the issue