2007 Hardbody, with about 100K on the engine. I just bought this truck a few months ago, and it's driven by a friend. It developed a rattle, so we immediately pulled the valve cover. Sure enough, the timing chain was actually loose.

Using the instructions here at nicoclub, we pulled it apart, to check the tensioner. While doing this, the chain spontaneously snugged up. Nothing seemed too worn (other than the oil pump gear on the crank), but we replaced the tensioner, sprockets, guides, chain, and seals anyway.

While we had it apart, I squirted carb cleaner and air through the oil galley feeding the tensioner, to try and make sure it was clear... I also tried to get a thin wire through, but had no luck at that. I can't say that I actually got it truly flushed out.

Put it all together, and all was well... for a few days. Now it rattles again, intermittently, on startup. Sometimes is quiet, sometimes not. Always quiets down after a few seconds.

I see two possibilities:

- The galley feeding the timing chain tensioner is clogged. Is it possible to get to this galley from the oil filter side, and "snake" it out?

- Possibly it's just a hydraulic lifter collapsing?

My friend runs 10W-40 oil. I've suggested using 0 weight synthetic (which did wonders for lifter noise in my Trooper). He just put some STP in, which was what he did in his other Hardbody (which now has 300K on the engine, and has been rattling on startup since 100K).

I'd be grateful for suggestions. If necessary, we can pull it all apart again, but I'd hate to do that without a plan to actually find the problem this time.

I was going to suggest that you have a noisy rocker arm. I did my chain but still have a rattle on start up. Watching my oil pressure gauge the sound goes away once I'm over 10psi.

I think the rattle on startup is kind of "normal" - my '97 did it during my entire ownership. The guy who bought the truck from me lives two doors down, has put another 150K on it, and it still rattles pretty bad - although he's "old school" and starts it like a 1955 Buick (accelerator pedal floored) and revs the hell out of it, so I guess it builds pressure fast that way

I agree with your idea of trying a zero weight oil, and I would also recommend using a factory or other quality brand oil filter that has an ADBV (anti-drain back valve) that holds oil in the filter after you turn the truck off. I always used good filters, but he mentioned that the rattle got worse with some cheap filters he was using... I gave him one left over out of my stash and he said that helped.

Heath

I too have a cam chain tension issue with some serious rattle. Usually around 2.5-3 grand. Hopefully within a few months I will have time to tear down the entire engine and rebuild it. And not hopefully. I already have time off of work in march to do it all. If I find anything then, such as a clogged oil gallery, Ill let you all know.

If you find anything in the mean time, keep me posted. I would really like to fix it....

I own a 1997 pickup with the KA24E, had start-up rattle for several years, start-up rattle should be fixed, there is a risk of jumping a tooth and messing up your engine.
I had success eliminating start-up rattle on my vehicle and several others fabricating a cup bushing.
Install by removing valve cover to gain access to hydraulic tensioner.
Cup bushing is fitted for length to remove excess chain slack produced at cold start-up.
Install over end of piston of the hydraulic tensioner, this holds bushing in place and still allows the hydraulic tensioner piston freedom to apply its pressure against chain guide when the oil pressure builds up.
I have seen this method produce 100% success in eliminating start-up rattle on the KA24E engine.

>>Cup bushing.

Best idea I've heard yet. Wish I would have heard it before replacing my tensioner!

Evan,

Glad to hear you got it fixed.
If the noise re-surfaces and you want to look into the fix I described look me up, I have a couple laying around here and will be setting up to run another batch soon.
[email protected]

Jim

I am so grateful for the solution that Jim M has posted in this forum. (as well as the others) Putting a 1/4 inch "cap" or extension on the tensioner piston saved my bacon.

I found this solution on my third time around, opening up the timing cover and scratching my head, cleaning out the oil pressure feed port, installing new main and rod bearings from below, heavier oil, etc. All the things I found mentioned, but only the tensioner-piston-extension trick did it.

I also took one further step and removed the exhaust side chain guide completely. Gone. Other posts said Nissan mechanics were doing this a long time ago and with a taught chain I felt I could run the risk of the experiment. Anything to quiet things down.

Final item I tried was to tighten up the tension on the tensioner spring just a hair by installing a spacer (a small nut) inside the piston itself, held in place by the spring.

I am very happy with the result so far.

May have been not required, but I did epoxy the spacer-cap-extender onto the end of the tensioner piston itself. My thinking was that I did not want the piston to be able to retract far enough for the "cap" to fall off.......It could be overkill but it made sense to me in the middle of this surgery.

Thanks Jim. You are a lifesaver.

anyone with similar troubles can contact me at [email protected] if they would like to ask questions and I will be glad to help. Jim also has the extension part perfected and he was more than willing to help me.

jimM wrote: ↑

Wed Nov 20, 2013 3:37 pm

I own a 1997 pickup with the KA24E, had start-up rattle for several years, start-up rattle should be fixed, there is a risk of jumping a tooth and messing up your engine.
I had success eliminating start-up rattle on my vehicle and several others fabricating a cup bushing.
Install by removing valve cover to gain access to hydraulic tensioner.
Cup bushing is fitted for length to remove excess chain slack produced at cold start-up.
Install over end of piston of the hydraulic tensioner, this holds bushing in place and still allows the hydraulic tensioner piston freedom to apply its pressure against chain guide when the oil pressure builds up.
I have seen this method produce 100% success in eliminating start-up rattle on the KA24E engine.

Jim I would love to know more about this solution.. TIA