HoneyBadger

Gentlemen (and ladies where applicable),

A while back I was able to get a hold of this sweet little '85 4x4. It is a great little truck and mostly unmolested- took quite a while to find.

Backstory: I bought it from the original owner's brother, still has the window sticker and everything :-) it has 193,000 on the clock and is quite possibly the smoothest running 22re i've seen. I have put about 7,500 miles on it and enjoying the crap out of it.

Possible issue: Driving to work the other day I was stopped at a light. Looked down and noticed RPMs Oscillating between 1000 and 1300- I found it odd but kept driving anyway, I figured I would be chasing a vacuum leak later when I got home. Fast forward through the work day- I am getting in the truck to leave, cranked it and had this stout screeching noise not unlike a slipping belt. I did the only honorable thing and passed it off as a slipping belt :-) Got to the house after a 23 mile drive, popped the hood (by this time the rpms are holding a steady 1000 rather than the usual 750ish) and immediately made note of the "timing chain running against the housing noise"- a pretty unmistakable noise in an easy to identify location.

At this point I have parked the truck in the shop, torn the valve cover off expecting to see a demolished rail and generalized carnage, what I see instead is a perfectly intact timing set and a fairly clean head for the mileage. It is hard to tell if the timing set has been replaced since I'm not sure I've ever seen a "factory" set right next to any replacements, but I assume it has given the mileage and the fact that the dude I bought the truck from "thought his brother had had the engine rebuilt" at some point.

What I did find odd though is that the "bright" link that I thought was supposed to be parked on top of the index marks was hanging out 6 links counterclockwise of the mark (see attachment).

Assumptions I've made so far: My tensioner is giving up and I probably need to lay in a timing set. Additionally, I figure the timing set has already been replaced "at some point" and the person that performed the duty didn't use the "bright" links to their full capacity...

If it jumped 6 links wouldn't I be putting a head on it? Also, wouldn't the link tend to jump in the clockwise direction?

I haven't gotten too far into it and if I don't have to tear it down, I'd rather wait. As far as precise measurements what I can say is that the chain has about 5deg of crankshaft rotation worth of slack while on the truck- this seems acceptable to me but perhaps everyone here can shed a little light on the matter.

HighLux

Bright link is lined up on assembly. 2 sprockets are diff sizes, so it will not line up everytime.

If you jumped timing...you would know it. It would buck...backfire...etc.


Screeching...maybe waterpump? tensioner? fan? poke around some more.

snobdds

That thing is way off...if it's at TDC on the compression stroke.

It can jump time due to a worn out tensioner. I would get it to TDC on the COMPRESSION stroke and see where your marks are at. To make sure your at TDC, the two valves on #1 should be loose.

Take a picture and post it...then we can tell you for sure if you jumped time.

HoneyBadger

Yeah, I got to thinking after a while and figured the links only line up on occasion after install. I'm beginning to think it may be a wasted bearing somewhere- the more I listen the more it sounds like a grinding bearing rather than a chain skidding across something. I poked around with a screwdriver to my ear and found most of the noise SEEMS to be coming from the water pump housing. The noise goes away if you rev it but seems to come back after a while of idling. I buttoned everything back up and decided to drive it 'till the water pump pukes or something else makes itself blindingly evident.

As long as I don't have any unscheduled projects come up I'm about to take on a knuckle rebuild. The knuckles seem to have an endless supply of gear oil to distribute evenly across the backs of my wheels/tires. I've been through most of the threads on here and have the FSM to help. Anyone have any pointers on problem spots? I've heard cone washer removal can be a pain...

donomite49

cone washer is easy if you do it correctly.

tap the flange lightly just above the cone washer/stud with a steel (brass is better if you have one) hammer and the cones will loosen up or pop out.

donomite49

check timing by setting crank pulley on TDC mark, #1 piston at TDC and rotor button pointing at #1 lobe on dizzy and #1 cylinder valves are closed. think there is an o mark on top of the cam sprocket too.

go ahead and change the water pump before it seizes and leaves you stranded like mine did on my 79 4x4 about 40 miles from home.

build it dont buy it

pull your belts one at a time and start it, you will most likly find it is a tenstioner pulley. i I I I had the same thing happen. let us know what you find.

cman1

iTrader: (1)

just get the whole timing chain and cover,water pump,oil pump kit from ted at engnbldr.com...you will not regret it!!!!! oh,and wabbit has a great knuckle kit!

HoneyBadger

Ok, got to work this morning fine. No strange squeaks, grinding, or rubbing. I guess that is just going to be a sporadic thing. I did however still have the funny idle. Brakes have no effect on the idle- it does the same thing whether I'm on them or not.

I looked at it closer this morning, here is what is going on: Sometimes it will have a constant high idle, about 1200 rpm. Other times idle speed is normal, around 780. Thirdly, sometimes the idle is fluctuating... It will slowly (over 2-3 seconds) rise to about 1300, quickly drop down to 750 ish and immediately start slowly heading back up to 1300.

I put a new AAV on it about 2 months ago for an unrelated issue (It didn't like to start cold or after heatsoak). This problem seems to be a little too "fast acting" to be the AAV, but you never know. Also I checked and adjusted the TPS a while back but it may be time for another. Thoughts?

Both the noise and fluctuating idle came up at the same time, that is the main reason I suspected the timing chain, now I'm fairly certain I have two unrelated issues.

HoneyBadger

I should add that the A/C has no effect on this either. I am beginning to think it may be something such as the AAV stuck open for some reason. I guess my next step is to pinch the air hose going to the TB and look for a change. If I don't get anywhere there I'll move to the TPS. I did test the new AAV before I installed it and everything checked out, also I noted that after a good cold start yesterday (about 45 deg F) the truck had a good high idle of about 1300 rpm. I left it parked and after about 10 min it had idled itself down to 780, so at least at that time it seems like the AAV worked properly.

HoneyBadger

Ok, for anyone who may have been watching this, I believe I have gotten to the bottom of it. The short story of the whole thing is that I had de-greased everything under the hood a couple days prior to all this weird stuff showing up. Turns out that the belt squeaking/rubbing noise was a freshly de-greased tensioner pulley.

The funny idle was a little more difficult to track down but it ended up being the freshly de-greased dashpot on the throttle body. Turns out that the dashpot was causing the throttle to stick VERY slightly open but not open enough to break the IDL circuit in the TPS. During that critical warm-up period while the AAV is still open it was allowing enough metered air in to raise the idle until it would hit fuel cut- this is what made the idle fluctuate like it was.

I threw a little spray lube on all the offending accessories and i'm pleased to report that everything is back to normal.

I still have to rebuild the knuckles though, I'm sure I'll be back for that.