2000 5.7L Volvo GSI loud knocking and misfire

[BLinindoll]

I just picked up a 2000 Chris Craft last weekend from Minnesota. It has a 5.7L Volvo GSI motor. Took it out the other day for an hour or so and it ran great. Had about a half a tank or so according to the gauge. Today I took it out and within the first hour I noticed a very light hesitation on throttle up once in a while. Well, we parked for about 2 or 3 hours and then took off. Just after taking off I noticed a very loud knocking. I opened the hatch and sure enough, under a load it started knocking bad at about 1500 RPM's or so and got louder the higher the R's went. I also began to notice it seemed to be misfiring. Seemed like it was a pretty steady misfire, but I could be wrong. At this point it had between an 1/8 and 1/4 or a tank. Keep in mind I just picked this boat up, so the fuel has probably been sitting since last season. Could this just be old fuel and since I let it get so low it might have started sucking up crud in the tank? Maybe due to ethanol? As far as I know it just had a tune-up end of last season. Would detonation cause that loud of a knock, almost like metal on metal? I just put 25 gallons in it and brought it home, I'm gonna try and run it on the muffs to see if the misfire is better. Would the misfire make the engine knock like that?

Here's another question a little off topic. Since I bought it through a broker do they have to offer like a 30 day type warranty if the engine is actually bad, or is it just like private party as-is? Am I screwed if it actually is a rod knock or spun bearing or something or am I protected in some way because it was a broker and not private party?

 

[BLinindoll]

Re: 2000 5.7L Volvo GSI loud knocking and misfire

I just ran it on muffs. Seems to be a steady misfire so I started pulling wires. I noticed a change in all cylinders. Number 4 cylinder made the least amount of difference, but still some. When it's on the muffs it does not knock, but it definitely has a steady misfire. Would a bad misfire cause that bad of a knock when under load?

 

[Bondo]

Re: 2000 5.7L Volvo GSI loud knocking and misfire

Ayuh,... Did you Check the Oil,..?? How about the other fluid levels,..??
Other than the Gas I mean,....

 

[BLinindoll]

Re: 2000 5.7L Volvo GSI loud knocking and misfire

checked oil and looked brand new. doesn't smell abnormal, and no metal. I did a compression test. Bad news. here are the results....

1. 190
2. 185
3. 0
4. 150
5. 0
6. 150
7. 190
8. 195

Thinking it's a carbon issue. Apparently the guy never beat on it and always putted around. I'm thinking when I opened it up a few times it loosened a bunch of carbon up, now maybe having valve issues? Thinking maybe the knock is the lifters hitting the stuck valves? Would it only do that under load? Cause it doesn't knock on the muffs... just runs like crap.

 

[maxxman04]

Re: 2000 5.7L Volvo GSI loud knocking and misfire

a knock sound, and no compression in two cylinders is catastrophic news my friend. in my experience, the combination of the two equal a blown motor. sounds like you've thrown a rod or two. however, just to check your theory, pull the valve covers, disconnect the coil wire from coil to distributor, crank the motor, or have someone do it for you, watch all the valve springs. if all of them move up and down as motor is cranked, you do not have stuck valves.

 

[BLinindoll]

Re: 2000 5.7L Volvo GSI loud knocking and misfire

i dont think it is blown. i forgot to mention that i checked the vacuum and it looks fine. doesnt bounce around at all. leads me to think i have some bad exhaust valves/seats. also the index-card-on-the-oil-fill-cap trick checked out fine, so there is no positive pressure outside the combustion chambers. that also rules out rings. and again, aside from the motor missing, there is no knock or any irregular sounds when it is on muffs (no load) and i rev it up. i can give it bursts up to 4500 rpms and it sounds fine. it only knocks when under a load. i guess ill find out in a few hours. im on my way home now to pull the heads.

also, i know i didnt throw a rod... again, the lack of sound when not under load (i would think youd hear the rods rattling around even without a load), plus i know that both cylinders that had no compression are still moving. they still push a good amount of air out of the spark plug hole when turned over.

 

[maxxman04]

Re: 2000 5.7L Volvo GSI loud knocking and misfire

it's still possible to have blown motor. however, is the noise a rattling, pinging type, or knocking? all are different. pinging generally has to do with timing, or bad gas. yes, the knocking is a sign of a thrown rod. there's a possibility that a couple pistons now have holes thru the top. still rotating normal, but now, no compression. watching the valves as someone turns motor over will rule out valves most of the way. by compression check, there is obviously a need to probably remove heads and see what happened. good luck.

 

[Don S]

Re: 2000 5.7L Volvo GSI loud knocking and misfire

You could do a partial leakdown test. just to determine piston or valve problem. But with 2 cylinders with absolutely 0 compression, I would be pulling the heads.

 

[BLinindoll]

Re: 2000 5.7L Volvo GSI loud knocking and misfire

I completely agree Don. Unfortunately I don't have access to a leak down tester, so I'm just gonna pull the heads.

 

[BLinindoll]

Re: 2000 5.7L Volvo GSI loud knocking and misfire

What's confusing me the most is why the hell the thing runs like it has single misfire, and not more like it has 2 dead cylinders and 2 more cylinder that are 40 psi lower than the rest.... the thing should run like ****, if at all.

 

[maxxman04]

Re: 2000 5.7L Volvo GSI loud knocking and misfire

welcome to GM based motors. in dealing with automotive 5.7's for a couple decades, i've seen these motors do crazy things.

 

[BLinindoll]

Re: 2000 5.7L Volvo GSI loud knocking and misfire

Problem found....

2 bad headgaskets! YAY! Lol.

The side with the cylinders with 150 psi was just starting to blow out. one side of the gasket was gone and the other side was on its way.

The side with the 2 dead cylinders was completely gone between the 2 cylinders. about an inch of gasket was gone.

Both sides were going bad in the exact same spot, right smack in the middle.

The rest of what I can see looks beautiful. The pistons are perfectly even colored. No carbon build up. Cylinder walls look perfect. You can still see the cross hatches with no scoring or staining whatsoever.

I am planning on checking the heads for trueness, obviously, but what would cause this? I don't think it would be due to overheating, and I don't really see the heads being warped in the spot where they went bad. Has there been a problem with the head bolts loosening over time or stretching on the center cylinders of these 350's? As you should whenever you remove the head bolts, I am definitely going to get news ones now anyways.

 

[BLinindoll]

Re: 2000 5.7L Volvo GSI loud knocking and misfire

I just had it running literally a few minutes before i started the tear down and everything was dry that should have been. no water issue is what im saying. and i dont know if it was ever running as good as it SHOULD have been. like i said, i just bought the boat last weekend. I think it just finally "went" the other day. i dont think it happened that quickly by the looks of the gasket.

as far as having a shop check the head, im perfectly capable of reading a feeler gauge under a good straight edge. i went to school for automotive technical services. not trying to sound rude, just letting you be aware of my automotive experience and background.