SOHC Timing Chain question

[pmkls2]

I just pulled my valve cover to replace the gasket and inspect the timing chain guides. The guides appear to be in great shape, but there is some slack in the chain. So I was wondering how much slack is normal, and how do you tell if the guides are the updated versions or not ?

Phil

[TrunkMonkey]

looking down through the valve cover to inspect the condition of your guides can be deceptive. i thought mine were okay until i pulled the front cover. the bottom half of one guide was completely gone.

do you have any rattle at startup? iirc, the updated guides have a metal backing. the best way to tell is to pull the front cover.

-demetrius

[deviousKA]

Yes exactly like demcj said, looking down from the top can be very decieving as far as guide condition. Many i have done have looked ok until i pulled the cover. Only way to roughly get an idea of your chain slack, without pulling the front cover, is to look down from the top at the chain tensioner. You should be able to see the small tensioner cylinder pushing out on the left-side chain guide (left if your looking at it from the front of the car). That cylinder should not be pushing out 1/2" or more, 1/4" is about normal for a good used chain, and with a new chain it should be about 1/8". This is not a definate guide to follow, but i have done a lot of customer timing chain/guide replacements, and this is my rule of thumb. Make sure that you roll the engine over a tad bit by hand with the crank pulley, to make sure the camshaft hasnt rolled back when the engine was shut off.

You might, or might not be able to tell if you have the updated metal-backed right side guide (right side if your looking from front of car). The updated guide still has a plastic peice that covers most of it up. If you grab a flashlight and look, you should be able to see the bolts that attach that guide. The factory plastic guide uses longer bolts with large shanks, the metal back guide uses standard allen-head bolts with lock washers.

You can also look the chain itself and see if it is oem-style or aftermarket replaced. Oem the ka24e uses a high quality 06E chain that is much more heavy duty, than the 06B common replacement chain. Some of the links of the chain will be labeled 06B or 06E. Imho, the 06B chains are junk, and many that you get in timing kits even have split rollers! This may be of little importance, but i thought i would add.

Good luck, and if you do end up pulling the front cover, take your time, especially during reinstallation.

[pmkls2]

Well, I really couldnt tell about the guides. They appeared to have allen head bolts, but that is all I can tell. For now it is okay, because I was just making sure that the drivers side guide was still intact. I will be replacing the chain soon anyways. I dont have any timing problems right now, but I am a perfectionist and like to know my car is in tip-top shape. But, since it is a roller style chain is it absolutely necessary to replace the cam and crank gears when replacing the chain ? I'm a general motors technician and I cant count how many times I have replaced a chevy timing chain and not replaced the crank gear. Thanks for the tips,

Phil

[TrunkMonkey]

But, since it is a roller style chain is it absolutely necessary to replace the cam and crank gears when replacing the chain ?

you don't have to.

on my personal car, all i replaced were the guides, guide bolts, and the tensioner. the chain and gears were in such perfect shape, i didn't even bother to remove them.

-demetrius

[pmkls2]

Well, what would you consider good shape, and how do you tell? I have 142k miles on the car and when I bought it it was a 1 owner with 96k on it. I have no idea of the service records on the car, but I would guarantee it is one of the cleanest '90 model cars you will ever see.

[pmkls2]

P.S. I keep forgetting to say that SOMETIMES it has a rattle at startup after sitting overnight, but it doesn't do this every morning.

[TrunkMonkey]

Well, what would you consider good shape, and how do you tell?

inspect the rollers on the chain. if any of them are split, or have an hour glass shape, replace it.

i can attest to the quality of the oem chain. the chain that came with the timing kit i had looked like weakness compared to the 100k mile oem one on my car.

-demetrius

[pmkls2]

Well, I have decided to do the whole thing when I go in there chain,gears,guides, and tensioner. I noticed that my car rattles like crazy if you let it sit for a couple hours(I just never listened for it before to notice). And I did find a picture of the updated guides and I do not have them on my motor. And since I work right next door to nissan, I will be using ALL genuine nissan replacement parts. I gotta get this thing in shape because I am going to be hopping up the motor soon and I need it to be in tip-top shape first. Thanks for the info,

Phil

[pmkls2]

Okay, so I ordered all the stuff to do my timing chain from nissan today. Other than all of the bolts and everything else in the way is there anything I need to do to get the timing cover off ? For example, does the distributor have to come out, and does the oil pump pickup bolt to the front cover like some nissan engines (pulsar)?