walldaddy

My son has a 1985 C10 Custom with a 305. His first vehicle. Given to him by my father in law. Truck sat for about 5 years. We brought it home, tuned it up and got it running. He's been driving it to school for a few months. Yesterday as he was pulling out of the driveway, it made a pop and died. He got it started and pulled back into the driveway. Last night we took a look at it. I can get it to start but it will not idle and sounds horrible. Almost sounds like the distributor is 180 degrees off but I know its not since its been running fine. Checked plugs and they had a strong smell of gas and oil. I also checked the fuel pump, line in a bottle and cranked engine, its working fine. I'm thinking maybe something in the timing. Any suggestions will be much appreciated.

Kazoocruiser

You might want to pull the distributor cap, and use a wrench on the crank nut to rotate the engine slowly back and forth to verify there isn't any lag time to the distributor rotating. You may have a cam gear that has started to de-laminate. GM used nylon-coated cam gears and when they come apart, the valve and distributor timing goes bad.

How many miles are on the odometer?

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https://www.google.com/url?sa=i&rct=...41173178765788

walldaddy

Kazoocruiser, thanks for replying. It has 180,000 miles on it. I will pull the distributor tonight and try this. I will post my findings. I kinda wondered if that could be it.

Kazoocruiser

Hi walldaddy, welcome to the forum.

I don't know what you or your son's level of expertise is, but I'm going to offer some coaching from the sidelines.

If you go to the third link I provided, you will see the results of a stripped nylon gear, in a 305, and the resulting damage to some other parts. On a low compression engine, 8.6:1 or below, a stripped gear might only result in loss of compression and valve timing, but if your son's engine did what seems to have happened in the link, then not only the gear, but the push rods and valves may have been damaged due to collision with the piston interference with the valves. The first attempt to crank the motor after the pop did the damage. The sounds you are hearing from the motor now are the screaming demons that got trapped in the meyhem. They are rattling the likely bent push rods in an attempt to get out of their prison. Weird stuff happens around halloween. Can you tape what it sounds like and post a video somewhere? You could call it, "Car Sounds from Hell."

It might be time to sit down with your son, since he owns and was operating the truck when the damage occurred to discuss some options. One option is to replace the gears and chain, and repair any damage to the heads on an engine with 180,000 miles on it. Another option is putting a crate motor in it, which restores new performance to a vehicle with a current motor with 180,000 miles on it,which after it is repaired, will still have 180,000 miles on it, which is hardly an improvement.

I'm going to guess that the truck is carbureted. If that is the case, the lower end sealing capacity of the rings is about gone.

So maybe another option is pulling the motor and doing a complete rebuild, including new oil pump. I think you are going to have to replace the one you have now, or at a minimum, pull the pan to clean the screen of all the metal shards and nylon bits that fell into the pan and were picked up when the gear disintegrated. If that is what has happened.

Personally, it's not my money, and it's not my truck, but your son got the truck for free. Being that it is his wallet, skills and time on the line, he might want to put a new engine in it which might extend the effective use of the truck so that your son can pass this gift-horse, which now has some missing teeth, forward to his own future son-in-law.

I know whatever decision gets made you will be in his corner, willing to hand him tools.

Not ever having done a gear replacement like this myself, I'd like you to document your progress with pictures. That way it becomes an on-line educational archive. It might duplicate someone else's work, but there isn't a thing wrong with data redundancy.

I've been doing a bit of that myself while I am restoring my 1981 C10 with an integrated head 250 / 4.1.

You can check it out / like / subscribe, @ https://www.youtube.com/channel/UC_W...foLyeDq_WQPNmA

/s

walldaddy

Kazoocruiser, thanks for the info. Gonna check timing chain today. My son is 17, minimal skills and $ but is willing to do whatever it takes. I know enough to be dangerous, lol. I have a 350 4bolt that he can have/rebuild if it comes to that. Hoping we can fix what he has, this truck is his pride and joy. I will definitely post my findings and will probably have more questions once we get started. Thanks for your help.

walldaddy

So I changed the timing chain, water pump and fuel pump. Put it all back together and it's running real bad. Got it to start but won't idle, sounds like its the timing. It's not 180 out, checked it. There is so much pressure inside the motor that it's blowing the pcv valve out of the valve covers. There is oil inside of the distributor too. Very frustrating to say the least. Any suggestions? Maybe it is time for a rebuild, did not want to do this right now.

kevinkpk

do a compression check, see what cylinder is leaking into the crank case

Kazoocruiser

Hi walldaddy,a lot of weird stuff happens during Halloween, so maybe what you are dealing with is no exception.

Before I can offer directions to go, I meed information about where you have been.

You mentioned the chain. You didn't mention the gears. Did it turn out that the cam gear was stripped?

Did you pull the valve covers to verify that there weren't any bent push rods?

If you had a valve hanging open and a piston smacked it, the valve may have cracked a piston. That might account for your excessive crankcase pressure.
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if you have stuck valves, that would account for some of the poor operation you are describing.

At 180,000 miles, I am not surprised that oil is inside of the distributor. They have seals internally that wear out. It probably doesn't help that you have too much pressure in the bottom end.

Like kevinpk indicated, a compresson test will tell you a few things. A compression leak-down test would give some information.

P.S. walldaddy, I don't know why you mentioned you don't want to do a rebuild. Seems the hardest part of the job would be is handing tools to your son.

If it is any consolation, you got the engine running, something it wasn't doing two weeks ago.

walldaddy

Kazoocruiser, yes cam gear was stripped and had a lot of slack in the chain. I did pull the valve covers off. The #5 cylinder rocker arm was very loose. I adjusted the valve, just that one, and checked the push rod on that cylinder and it was fine. I did not check every push rod, but I will. I will have to get a compression gauge and check it, mine is broke. I mentioned that I didn't want to do a rebuild right now because its a month before Christmas and money gets tight, lol. My son does not have much money so I would be footing the bill for the most part. We just wanted to be able to drive it until spring time and then decide what route to take. When I do the compression check I will post my findings. I thank y'all for your help and insight.

oilcanhenry

If you buy a new timing chain, get a Cloyes.timing chain. Things are built like a rock. "Mo-parts" used to juse a nylon coated timing chain, which was one POS. Who cares if
the TC makes a little noise?