ironhead1974

Just bought a 90 G20 van. When I bought the vehicle I noticed it had a slight knocking noise almost like something was loose under the van.

I started it up and looked under it and saw nothing that would be making the noise. I removed the engine cover and started it and tried to pin point the sound in the engine and still couldn't isolate where the sound was coming from. I would listen to each head and it sounded like the noise was coming from more the center of the engine, I thought perhaps it may be the water pump toward the front.

The van would run fine, no loss of power, tranny was shifting smooth, the only problem was an audible knocking noise at times. At idle it wasn't that audible, more so when I would give it more gas. So, I also thought it could have something to do with the throttle body injection.

Anyway, took a little road trip over very mountainous roads. 100 miles one way and 100 miles back. And I was thinking how well it was running and how good of a purchase I made, and then it happened.

As I was ascending a mountain the knocking noise changed from the normal sound to almost a sound where your muffler blows a whole in it. Almost like the internal knocking noise became an external rattling and grinding. Needless to say the power I had going up the mountain dropped off considerably, almost to a creep. I pulled over as much as I could with cars behind me and decided I had to go a little farther. I got up the mountain a little more (maybe 50 feet) and then I had no more power. I had to pull off the road and it shut off on me. I let it cool off some and checked the radiator and it had coolant in it, the temp gauge was not reading hot. As we were rolling it up on the roll back, engine oil started pouring out onto the bed of the rollback. So I guess I have a hole somewhere in the block or head or a seal is blown out.

I tried to start it again and nothing, the engine wouldn't turn over at all, and still won't. Any help of what this sounds like and what I should be looking for when I get around to tearing it apart is greatly appreciated.

Thanks


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Update
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Heres an update on whats going on.

I removed the head covers to see what might be going on with the push rods and valves and everything is there, the push rods are tight and none are broken. The valves and springs are all there too. I even took a flashlight and looked down into the head to make sure the push rods went the whole way down through the head and they do. So, its not them. As I stated, I didn't hear the tapping coming from the heads, it sounded more internal or more toward the center of the engine.

I drained the oil and found some very small metallic pieces in the oil, none stuck to the drain plug, not sure if its magnetized or not. Pulled the flywheel cover off, because the oil that ran out onto the rollback was coming from a hole in the bottom of the flywheel cover. I noticed some oil on the flywheel. I guess this oil is coming from the rear crankshaft seal.

There are no holes in the oil pan or engine block.

Could the problem be the oil pump itself? would the oil pump make a tapping like noise if its about to go? Next I will try to remove the oil pan to inspect the oil pump and inspect what I can see of the crankshaft. Also as I stated, the engine seemed to be seized up after what happened. Could damage to the oil pump or the oil pump not working cause this?

I believe the problem is not in the heads but in the bottom end of the engine. So if anyone has any ideas what to look for any help would be greatly appreciated.

Thanks.

Tommy

I say a spun Rod Bearing??? thrown rod?

therewolf

This may be a total wild goose chase, but it will only take about 5 minutes, so what the hell. Pull the distributor cap and check the rotor(and cap) for damage?

mudmaniac

I agree with Tommy, spun bearing.
Drop the pan and take a look.

EvansBlue

I think he did that when he posted this thread.

Gwampa

Ain't that the truth....in this case the advice couldn't get much better.

old dog

i would be surprised if all it was a spun bearing sound's like a broken rod ,but you will have to pull the pan to find out !it cooked the rear main seal letting it leak out . water pump bearing is a rotational noise .