Recently picked up an '89 W250 with an LA 360 that is in mostly solid mechanical condition, but with a ton of rust on the cab. It's started, ran, and drived really nicely since I got it a few days ago, but started giving me trouble yesterday. Started it for the first time that day with no problems, pulled it out of the garage and could hear a slight rattling noise. Once I got on the street and gave it a bit of gas, the rattling intensified and then the engine stalled all together. Electrical was still functional so I could hit the starter & turn it over, but it wouldn't fire off and was making quite the rattling racket when the engine was turning. I pushed it into my yard and went about my morning with another vehicle until I could get back to it, then it suddenly started up just fine without any rattling noise. It does seem like when you give it any gas now it hesitates a bit, like it's close to stalling, but then it revs up just fine after that. Prior to this the throttle was very responsive, with no hesitation.

My guess is the timing chain must be very loose, and maybe skipped a tooth or two? Has anyone else seen something like this before, or have any different ideas? I don't want to dig my way down to the timing chain and find out it's actually fine after all. I don't have a timing light, but will be getting one soon to test that theory before getting to work.

 

You can check the chain by removing the distributor cap and position it at TDC #1 cylinder on the compression stroke. From there you can turn the crank and see how much slop you have in the chain and see if it's timed correctly. I don't think you would hear a worn chain the noise is something else. See if you can pin point the location where it's coming from. You may want to check what fuel pressure you have also. What condition is the cap/rotor plugs and wires in?

 

Good to know, I'll give all that a try. And unfortunately the noise has now stopped and I haven't been able to recreate it, so won't be able to track it until it decides to come back. I'll try leaving it to run for a while soon.

Cap looks fairly new from the outside, haven't checked the internals yet.

 

How many miles on the engine? You can check the chain like Moparite said. It doesn't need to be at TDC, just look for excessive movement. 5 degrees or more on the balancer timing marks is getting loose. I've seen them with nearly 20 degrees and how THAT engine ran is beyond me. The rattling could be ignition knock. That could be from old fuel that is stale. I had a Dakota once that developed a rattle and started stalling from the catalytic converter internals falling apart and plugging the exhaust.

 

Unfortunately not known - the PO didn't know exact mileage. The odometer reads 41k, but who knows how many times that's rolled over. From what I can see it looks like the original engine.

Didn't sound like ignition knock to my ear, was more like a rattling chain or maybe even grinding? Something close to that. Should be able to get out today to look into it more.

And it did have half a tank when I got it, but I have no clue how long that gas had been in there so that's a possibility, too.

 

Okay, got back out there and have a better understanding of it. The rattling/grinding noise appears to only be related to the starter, and nothing else. Sometimes on starting I get a lot of the noise and it'll refuse to start, sometimes it starts just fine. It will stall if I hit the throttle too hard, which is most likely what happened on the road yesterday because it did stall just as I was trying to take off.

The PO installed a push-start that I suspect might be related, because I have mixed success with recreating the noise depending on how hard I push the starter button. Not sure what that's all about yet.

Any thoughts on the stalling with too much throttle? It idles fine, and I checked the timing chain with the distributor and that looked good too. Might try cleaning the carb since it's been sitting for an unknown amount of time. I did also get one runaway throttle after starting that I couldn't recreate. I'll upload some videos with audio of everything.

 

Noise being made by the starter:

 

RPM stuck very high right after startup. Killed engine and restarted, then ran like normal.

 

Sounds like the bendix is not coming out all the way to engage the flywheel.
Accelerator pump not working correctly. May want to check the choke linkage/kick down cam also.

 

Thanks for the info, I'll check that. Also going to try rebuilding the starter, or replace it if it's looking rough.