6.9 intake valve question

[Kevin 007]

Had an 85 6.9 develop a sudden and consistent, rpm dependent intake "chuff". The same chuffing that's usually related to a sticking lifter or a bad guide. Since it was consistent and didn't go away like a sticking lifter chuff often does, I figured that it would likely be a broken rocker or something related to that, or possibly a bad guide, but less likely. Cylinders 2 and 4 have 200 psi compression where all the others have 400+. The chuffing thru the intake happens when the cyl 4 intake valve opens. The rockers for that cyl are not broken or badly worn, the pushrods are also straight and not badly worn. However I noticed that the spring on the intake valve on cyl 4 rotates with the engine running, as if it has a spring rotator and the other intake valve springs do not rotate.

Question is....do the intake valves on these have rotators? I am thinking that I may be dealing with a bad head gasket between cyl 2 and 4, due to the compression numbers; but that intake chuff related to cyl 4 is the reason that the truck went under the knife as it was running decent but then started chuffing. Id like to see if I can get that issue sorted, which may restore compression on that cylinder and that truck might then run well enough to keep using for now.

 

[franklin2]

Make yourself an adapter to adapt shop air to the #4 glowplug hole. Loosen both cylinder 2 and 4 rockers till all 4 valves are shut, and then put some air to it and see where it comes out at.

 

[Kevin 007]

Make yourself an adapter to adapt shop air to the #4 glowplug hole. Loosen both cylinder 2 and 4 rockers till all 4 valves are shut, and then put some air to it and see where it comes out at.

Yes indeed. Will be getting on that asap

 

[Kevin 007]

Yup so pressurized cylinder 2, and had the pressure escape from cylinder 4 valves as I opened them manually (all rockers off). So the head gasket is bad and the rotating intake valve on number 4 is no longer a concern.

But I am still curious if the intake valves have rotators on these... I haven't done enough valve work on idi's to know.

 

[franklin2]

I don't know the answer to the rotator thing either. I know a lot engines only have them on the exhaust, not the intake.

 

[CDX825]

These engines do have positive valve rotators.

 

[Kevin 007]

These engines do have positive valve rotators.

On the intakes to?

 

[CDX825]

Yes both intake and exhaust.

 

[hacked89]

I did my valves not too long ago in my build and I recall the non turbo motors having rotators on one set and Turbo motors rotators on both.

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[cre1992]

Ill be following this thread as I am gathering some parts to do the heads on my truck.

I did my valves not too long ago in my build and I recall the non turbo motors having rotators on one set and Turbo motors rotators on both.

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Any parts you would recommend getting for the heads? I've heard using Comp Cams 910-16 valve springs?

Currently I've got all new lifters and pushrods. All the gaskets I need. ARP studs are on the way.

 

[IDIBRONCO]

Any parts you would recommend getting for the heads? I've heard using Comp Cams 910-16 valve springs?

Unless you're running a bigger cam or a lot of boost, there isn't much point to using the stiffer Comp 910 springs. They'll wear out your rockers quicker. Stock replacements will be fine.

 

[Kevin 007]

Unl

Uness you're running a bigger cam or a lot of boost, there isn't much point to using the stiffer Comp 910 springs. They'll wear out your rockers quicker. Stock replacements will be fine.

My thoughts exactly

 

[hacked89]

Ill be following this thread as I am gathering some parts to do the heads on my truck.



Any parts you would recommend getting for the heads? I've heard using Comp Cams 910-16 valve springs?

Currently I've got all new lifters and pushrods. All the gaskets I need. ARP studs are on the way.

I used the comp910 springs because I'll be running alot of boost.

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