disappointed during repair.

[FowVay]

Well, my 17 year old Nissan pickup truck had to come into the garage for some repair work this 4th of July weekend. I've had horrible chatter/rattle during start-up for years and after a recent oil change it got to the point that I was afraid something was going to come apart while driving down the road.

So, the first thing friday morning I pulled the truck into the garage and got to work. I spent about four hours removing belts, hoses, radiator and shroud, alternator, oil pan, everything that makes up the front of the engine. My work was not in vain though.

As I removed the front timing cover I was shocked. The entire timing chain guide had disintegrated and was laying in the bottom of the oil pan. The plastic part was long since gone and the metal part had nearly worn completely through. I'd say that this issue had been going on for about 5 years. The banana shaped tensioner guide was still intact and doing its job but it was worn completely out also.

I suspected all of this based on the sound of the engine at idle and start-up. But what shocked me was the amount of nasty, ugly varnish on the engine. The oil pan was OK but there was a small amount of carbon on various pieces and the area around the timing chain was HORRID!

I always cut my filters open and check things out and there's always an above average amount of carbon in the media and now I know why.

Going forward, I'm going to be doing more frequent oil changes and stick to Nissan's severe service intervals for everything.

I'm lucky the timing chain hasn't broken on this thing. The gears are horribly worn and the chain is stretched - likely due to excess heat.

 

[tony1679]

What oil brand/grade was typically used? Duration? Filter? This would help determine what went wrong, and possibly tell if something could have been prevented.

 

[Oil Changer]

So what is your plan for fixing it?

 

[Trav]

If it was running then it should be ok. Nice time to clean the top end and pick up tube.
I always liked this sort of work, nothing more rewarding than to take something banging and hammering and making run nice again.

What are you planning going forward with the job?

 

[fdcg27]

First, good for you for having done the work before the thing actually failed in use and the pistons kissed the valves.
It may be that the areas that are really bad just don't get a lot of oil by design.
If most of the engine looks good and only the timing case looks bad, it may simply be that not much liquid oil is supplied to it.
Either that, or there's an oilway or squirter intended to supply a steady stream of fresh oil to the chain that's clogged.
If you're as anal as most of us, I doubt that you were extending OCIs to an extent that serious deposits would form as a result.

 

[Merkava_4]

That's the problem with overhead cam engines, they need a timing chain guide/tensioner.

 

[The_Eric]

Super common on this engine. Like Trav said, once you get it all back together, you'll be quite pleased with the result- peace and quiet.

 

[nitehawk55]

17 years is a pretty good run if this is your first engine repair .

How many miles on it ?

 

[andyd]

I'm a less is more guy when it comes to engine repair. Varnish is one thing, sludge is another. Clean up the parts, make sure the oil passages are clear. replace the worn timing set and soldier on. Maybe switch to a HDEO or diesel rated oil. I liked my '72 Datsun 1.6 Pick up. It was a tough little truck.

 

[gregk24]

Originally Posted By: Merkava_4
That's the problem with overhead cam engines, they need a timing chain guide/tensioner.


Dont all engines with timing chains have guides and tensioners?

 

[Merkava_4]

Originally Posted By: gregk24
Dont all engines with timing chains have guides and tensioners?


Pushrod motors don't.

 

[FowVay]

The truck is 17 years old, has 260,000 miles. I am the third owner and the two previous owners were fairly cheap and likely used the cheapest products they could get and went a minimum of 5,000 mile intervals.

The maintenance history on the vehicle is very short. I put a clutch in it at 190,000 miles because the release bearing was screaming. I put a water pump in it about 5 years ago because it was dripping, I replaced the radiator about 2 months ago because it split the top.

So, for oil I'd say it had whatever was offered at Tires plus for the first 60,000 miles and Wal-Mart oil for the next 100,000. The filters were probably whatever cheap junk Tires Plus uses and then Wal-Mart superTech after that.

Since I've owned it (bought at 160,000 miles for $2,000) it's had nothing but name-brand stuff in a variety of flavors. Filters were usually OEM.

So I guess it has had a good run. I thought it should get at least 300,000 out of the timing gear set but I guess not. This reminds me, the teeth on the crank and cam sprockets were as sharp as knife edges. That thing was shot!

I'm in the process of putting it all back together as I type. I came in for some BBQ left over from last nights festivities. Man, day old BBQ cooked on the green egg is FANTASTIC!

 

[NHGUY]

I have a Caravan 3.3 with 98K and the timing chain has a mile of slop.I'm not looking forward to that job.

 

[The_Eric]

Originally Posted By: NHGUY
I have a Caravan 3.3 with 98K and the timing chain has a mile of slop.I'm not looking forward to that job.



They're not that bad to do...

 

[GSCJR]

Don't beat yourself up over it. As The_Eric has mentioned, very common on those engines. I also remember the 1.6L having the same issues with the timing chain guides.

 

[dave180]

Are you sure that the "carbon" pieces weren't the remains of the tensioner block disintegrating?

 

[antiqueshell]

Originally Posted By: FowVay
The truck is 17 years old, has 260,000 miles.

So I guess it has had a good run. I thought it should get at least 300,000 out of the timing gear set but I guess not. This reminds me, the teeth on the crank and cam sprockets were as sharp as knife edges. That thing was shot!!


The vehicle shouldn't be expected to owe you anything more at this point, 260k is a fantastic run. Now that you have made the repairs you'll probably see 300k without too much of a problem at least on the engine side.

 

[artificialist]

Originally Posted By: Merkava_4
Originally Posted By: gregk24
Dont all engines with timing chains have guides and tensioners?


Pushrod motors don't.

Back in the past, they may have been built without tensioners, but sometime later, tensioners were used with some OHV engines. The Chevy Caviler is the first example that comes to my mind.

Also, older OHV engines still had timing guides. There would be a triangular shaped block that matched the space between the upper and lower sprocket.

 

[HardbodyLoyalist]

You must have the 2.4L KA24E. I have the same engine in my '94 Hardbody.

As others have noted, it's an extremely common problem. And eventually you have to fix it, because the guide has no metal backing. Eventually, the chain rubs through the plastic and then starts rubbing the timing cover. It can eventually wear through the coolant jacket behind the water pump. The chain can also become so slack that it starts jumping teeth and, given that the KA24E is an interference engine, the results can be catastrophic.

With a little Google-foo, you can find numerous discussions about it on various Nissan forums, such as http://www.nissanforums.com/hb-truck/131401-97-ka24e-timing-chain.html.

 

[FowVay]

Well, I finished things last night around 9PM,, whew, that was the hardest job I've done in a while. I feel like I've played a quarter of professional football. I ache!

The timing chain guide definitely has a metal backing to it. The metal part is bolted to the block and the chain rides (rode) in the plastic guide which is just a cover over the metal. My plastic guide was in a zillion pieces in the oil pan. The tensioner itself is banana shaped and has what feels like a rubber coating on it. It wasn't in bad shape. My rattle and slapping noise came from the chain banging on the metal part of the guide.

The oil pan wasn't in horrible shape but it did have some deposits on it. The oil pickup screen and tube were clear and open. Hopefully I won't have any surprises with this truck for a few more years.