2008 Nytro Valve Problem

[MikeyZ]

Hey guys, I’m a newbie and I’m excited to join this group! I replaced my head gasket last week and I have been struggling to get both intake and exhaust valves closed at TDC. The caps and spacers are in their original order. I used an endoscope camera to confirm that the valves are open and they both seem to be about the same gap. Leak down test prior to the repair was good so something has changed. I'm hoping I don't have to go through the full valve clearance procedure and order new spacers since I haven't changed anything on the machine but the head gasket and it was running good other than pushing coolant into the overflow under load. I appreciate any advice you can give me.

 

[74Nitro]

Hey guys, I’m a newbie and I’m excited to join this group! I replaced my head gasket last week and I have been struggling to get both intake and exhaust valves closed at TDC. The caps and spacers are in their original order. I used an endoscope camera to confirm that the valves are open and they both seem to be about the same gap. Leak down test prior to the repair was good so something has changed. I'm hoping I don't have to go through the full valve clearance procedure and order new spacers since I haven't changed anything on the machine but the head gasket and it was running good other than pushing coolant into the overflow under load. I appreciate any advice you can give me.

It may just be that the shims are out of place which are located under the bucket.

 

[MikeyZ]

Good call, they were out of place, put them back and it looked better but still staying open.

 

[74Nitro]

Good call, they were out of place, put them back and it looked better but still staying open.

Of course, you have the lobes pointing up when checking?

 

[MikeyZ]

Yes, tried all positions while watching camera.

 

[MikeyZ]

1st image is intake valve with lobe up. Exhaust one looks like it’s closed now but at TDC with timing marks aligned with arrows both valves are open. See 2nd pics, intake then exhaust.

 

[MikeyZ]

Could valves be bent from the shifted shims? I rotated the crank a few times to get the tensioner to release, didn't feel resistance so I did a leak down test and it failed. That's what lead me to pull cams and check bucket shims. I'm thinking I may have to pull the head.

 

[74Nitro]

Did you have the head resurfaced?
Why did you take the engine apart in the first place?

 

[MikeyZ]

Thanks for the reply! Definitely had a blown gasket. Yes I resurfaced the head but don’t know how much I removed, I would estimate approx .005”

 

[74Nitro]

What part of Ontario are you from. I do have a good head for one of these engines.

 

[Mooseman]

I would imagine that you checked the valve clearances? When I did mine, all of them were too tight even before taking apart and I wound up having to re-shim them. I even had to buy a whole kit of shim buttons (expensive little buggers). I also lapped all the valves as they all had some amount of leakage (checked with alcohol and heads inverted). I also resurfaced the head myself using plate glass and emery cloth.

 

[MikeyZ]

What part of Ontario are you from. I do have a good head for one of these engines.

Sorry for the late response! I was away on vacation. I’m in Smithville.

 

[MikeyZ]

I would imagine that you checked the valve clearances? When I did mine, all of them were too tight even before taking apart and I wound up having to re-shim them. I even had to buy a whole kit of shim buttons (expensive little buggers). I also lapped all the valves as they all had some amount of leakage (checked with alcohol and heads inverted). I also resurfaced the head myself using plate glass and emery cloth.

Thanks for the info. Shims slipped and I didn’t know. Rotated the crank to engage the tensioner. Local dealer said I may have bent the valves so I will need to pull the head again.

 

[MikeyZ]

I would imagine that you checked the valve clearances? When I did mine, all of them were too tight even before taking apart and I wound up having to re-shim them. I even had to buy a whole kit of shim buttons (expensive little buggers). I also lapped all the valves as they all had some amount of leakage (checked with alcohol and heads inverted). I also resurfaced the head myself using plate glass and emery cloth.

Hey I took a break from this for a little while but I'm back at it now. I had access to a CMM and had the head measured. It was about .008" out of flat so I resurfaced it again and got it to ~.0015". Valves were straight but seals were rough. Lapped the valves and now I have the head back in, cams and chain installed with cylinder 3 at TDC but I'm having problems with my feeler gauges as it looks like the cam lobes are already starting to depress the buckets. Can I check clearance with Cam lobes facing up, referencing the spec from the manual?

 

[Mooseman]

Can I check clearance with Cam lobes facing up, referencing the spec from the manual?

That's how I did it with the head on the bench. Much easier that way.