Question about timing chain guide bolt

[bdw18_123]

Ok, I'm in the process of re-assembling my LT5 and I need some help. I'm working on getting all the timing chain guides, gears, chains, etc in. I've found all the correct bolts for the chain guides except for one.

Jerry's bolt info pdf doesn't list that one bolt and I can't seem to find any info about it anywhere. Jerry's pdf lists the 4 chain guide pivot bolts (the ones that go into the block) and the 1 short 20mm bolt that holds the passenger side fixed chain guide to the passenger head. It doesn't list the other bolt (I think there is supposed to be a bushing too) that holds the top of the long, straight chain guide to the driver's head.

See the picture below (using your pic, Lee :mrgreen:), the red arrow is pointing to where the bolt & bushing that I'm talking about goes.

Can someone here post a picture of that bolt and the bushing and also measure the bolt (thickness & length from bottom of bolt head in millimeters) so I have something to go by to find mine?


http://i13.photobucket.com/albums/a292/bdw18_123/DSCN0036.jpg

[bdw18_123]

I do not recall a bushing but have an 8mm x 1.25 by 30 mm bolt I think goes there :D
The Passenger side I think is the 8mm x 1.25 by 20 mm which you have. If there is a bushing, I am in trouble ;) as I have completely lost the bushing.

Well, there has to be either a bushing, or the bolt has to have a thicker shank than the threads. The 8mm x 35mm bolts that go into the other end of the chain guides (into the block) are too small for the that hole that the arrow points to in the picture. And yet, the threaded hole in the driver's head for that bolt is the same size as the 8mm thick bolts. That's why I'm thinking there has to be a bushing in there.

Dynomite, does that 8mm x 30mm bolt that you have that you say goes there, have a thicker shank than the bolt threads? Try putting that bolt in that hole and see if it moves around (side to side). If it does, I think you have the same problem I do, lol! Unless it's supposed to be loose like that, but I don't think so.

If anyone with their LT5 apart that knows what bolt goes there, if you could post a close up picture of it and post the dimensions of it, that would really help. Mine is lost so I need one.

I'm at a standstill with my LT5 until I can get that bolt. Arrrg, I hate when stuff like this happens... :-x

[bdw18_123]

:sign10: I cannot find any bolt with thicker shank for either side....the 8mm moves around in the timing chain guide hole on both sides.

Oh great. :rolleyes: I didn't even notice that. Why are those stupid holes like that? :icon_scra So I also have the same issue with the other fixed guide too.

So we need a picture & dimensions of the correct hardware that goes at the top of the fixed guide in the passenger side too. Hopefully someone here that knows will chime in soon because I want to get my LT5 together.

[limey]

You need these:

http://www.whiteracingproducts.com/index.php?main_page=product_info&cPath=10_55&products_id=162

[A26B]

OK. I have verified the info for bolts on the secondary timing chain guides, updated the bolt list on the website and made some changes on the website parts listings. here are the results.

LH Fixed Guide:
8x1.25x30 hex flange head. PN 11515792, no bushing
8x1.25x35 hex flange head. PN 24573579, bushing required

LH Pivot Guide:
8x1.25x35 hex flange head PN24573579, bushing required

RH Fixed Guide:
8x1.25x20 hex flange head. PN 12551177, no bushing
8x1.25x35 hex flange head. PN 24573579, bushing required

RH Pivot Guide:
8x1.25x35 hex flange head PN24573579, bushing required

Sorry I have been so long answering. Been really busy today.

[bdw18_123]

Thank you for the info Jerry! So that settles it, there are NO bushings at all and the bolts are supposed to be loose in the holes.

Kurt, the bushings in the link you provided are for the ends of the chain guides that are behind the timing chain idler gear, the ones that bolt into the block. I have all those (even have some extras). The bolts I'm referring to are the at the top of each fixed chain guide that bolt into the heads. Thanks for the tip though!


Ok, so that brings us to the next question:

There must have been a reason the holes in the top of the fixed guides were made larger than the thickness of the bolt. So when I go to install those bolts, where are the tops of the guides supposed to be positioned at since there will be some play?

You could either pull up on them (closer to the chain) or let them rest on the bolt (farther away from the chain). Is this to maybe provide another means of tightening the chains up when they become more worn out (other than the tensioners)? Dynomite, you suggest they are there for extra play depending on alignment of the heads with the block. I'm not so sure about that because the heads have pin/sleeve things at both ends so that the heads go on in the same exact spot each time. There really isn't any play between the heads and the block.

The service manual doesn't elaborate on the installation of the guides, it just says to install them, put loctite on the bolts and gives the torque value.

[bdw18_123]

I think the reason might be that part of the chain guide is bolted to the block and part of the chain guide is bolted to the head which distance may vary

You may be onto something there, Cliff! Now that I think about it, the gasket would be a bit of a variable in that regard. Not much, but enough I guess to merit making the hole larger. The heads can't move around side to side because of the pins/sleeves, but there is a bit of up and down play depending on how much the gasket compresses.

And if you install Jerry's head gaskets (which are thinner that the OEM's I think) those two holes in the two fixed guides would be even closer together.

Between us all, we are figuring out this mystery! :sign10: