Cam pulley hitting it's cover

[TANTO]

In the middle of the TB/WP and cooling hose job. Noticed my rear bank intake cam pulley is chewing into it's plastic cover. The terrible hack saw like edge on the cam pulley perimeter has ate about .040" into the cover in an arc about 3" long. Obvisously i could remove the pulley and file it down although it likely won't get much worse. I suspect the pulley bolt is real tight. I would have to figure out some way to hold the pulley(?). And since this is a revolving part taking off material doesn't thrill me although i guess these are not balanced parts. Anyone already done this? All original 92 w/29K. Bad on you Honda! Any experience? TIA

 

[NSXCessive]

In the middle of the TB/WP and cooling hose job. Noticed my rear bank intake cam pulley is chewing into it's plastic cover. The terrible hack saw like edge on the cam pulley perimeter has ate about .040" into the cover in an arc about 3" long. Obvisously i could remove the pulley and file it down although it likely won't get much worse. I suspect the pulley bolt is real tight. I would have to figure out some way to hold the pulley(?). And since this is a revolving part taking off material doesn't thrill me although i guess these are not balanced parts. Anyone already done this? All original 92 w/29K. Bad on you Honda! Any experience? TIA

I just did the TB with the same problem on my '91 project car. I ordered a new replacement cover & it also touches. I found by using a piece of plastic about 1/4inch in size against the cam gear to increase the distance between the gear & cover. I then tightened the 10mm bolts surrounding the cover, then removed the spacer, the key to making it fit was installing the rear valve cover it 'snaped' into position once I started the tightening sequence on the valve covers. There is a groove in the valve cover that snaps into the plastic TB cover. I did the job with the motor out of the car so it was easy to see & do, but more tricky in the car. I will post a pick of the old valve cover it started chewing through probably since the last TB job that was done on it.

 

[Kaz-kzukNA1]

Very common issue on early model NSX.

With the heat and design of the original covers,
the exhaust side of front cover and intake side of rear cover
can warp resulting in cam pulley scratching against them.



In fact, because of the very reason,
Honda modified the design of both covers later.

Very light scratch marking at the intake side on the
original design rear cover.
For this level of scratch, the cover can be reused.

The original design front and rear covers.

The later spec covers.

Front one is easy to spot the difference.

On the rear one, it’s bit difficult to see the difference but
the clearance has been increased around the
half moon shape recess as indicated.


So, if your covers were already warped and the scratch marking
was very deep, best to replace them to the later spec.

As in the above post, the key is to slot the upper edge of each
covers into the channel of valve covers.

Once you have placed the valve cover,
move it in side way to see how it fits against the front and rear covers.


Kaz




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[Larry Bastanza]

Hi Kaz,

Very interesting. In the US the covers have not changed at all based on the part number. I just may have to order a set to see what they did. Typically in the US if the number does not change, the part does not change. Do you have part numbers for these newer covers? Maybe N/A in the US.

BTW I have seen this for years, and have never seen any ill side effects, besides the ugly groove.

Regards,
LarryB

 

[greenberet]

I think the covers have changed in the US as well. The original covers in Kaz’s picture above look like 11820-PR7-A00 and 11830-PR7-A00 and the later spec covers look like 11820-PR7-A01 and 11830-PR7-A01. In my old US NSX parts catalog, the A00 versions are listed as being for 1991 NSXs and the A01 versions for 1992 and later NSXs.

I purchased the A01 versions from a dealer in the US in preparation for an engine service. I’m holding them in my lap as I write this and they look like the later spec covers in Kaz’s picture above.

 

[Larry Bastanza]

I think the covers have changed in the US as well. The original covers in Kaz’s picture above look like 11820-PR7-A00 and 11830-PR7-A00 and the later spec covers look like 11820-PR7-A01 and 11830-PR7-A01. In my old US NSX parts catalog, the A00 versions are listed as being for 1991 NSXs and the A01 versions for 1992 and later NSXs.

I purchased the A01 versions from a dealer in the US in preparation for an engine service. I’m holding them in my lap as I write this and they look like the later spec covers in Kaz’s picture above.

OK, that makes more sense. I started at 1995 model year in the catalog. I did not realize how early this change took place.

Thanks,
LarryB

 

[NSXCessive]

Hi Kaz I just the TB service on my Project Rebuild '91. The original cover has also had the cam gear eat into the cover a bit. The brand new revised cover I got a few weeks ago once installed also made contact with the cam gear.

I wound up loosening all the other covers to see if there was some more play in one direction. I used a piece of plastic between roughly 1/4inch to gently force some distance between gear and cover. Then applying 1/2 torque on the cover screws. Then installed the valve cover and re-seated it a few times wiggling left to right and then finally got it to 'pop' into position without making contact with the gear.

Went back and torque all the valve and cover bolts down. I wish I would have taken a pic of the issue showing how the new covers still makes contact the problem still exists but can be corrected by reseating the new cover(s) a few times.

 

[JD Cross]

NSXCessive

Are you talking about the cam pulleys rubbing inside the valve covers, or the engine dampener pulley rubbing on the lower belt covers?

Jim

 

[angus]

NSXCessive

Are you talking about the cam pulleys rubbing inside the valve covers, or the engine dampener pulley rubbing on the lower belt covers?

Jim

Did you look at the pictures above?

 

[JD Cross]

Did you look at the pictures above?

Yes my question was regarding the valve cover adjusting by NSXCessive