4.3 Engine knocking, burning ton of oil,

synergy141 · Sep 4, 2010

Hi, just bought a 1999 Chaparral with a 4.3 volvo with SX leg. Before I took it out I checked the oil level, it was fine. Took it for a good run just cruising at 3000 rpm and I noticed the oil pressure was dropping slowly. (When I left the dock oil pressure was at 40) It then got down half way between 40 and the next line down at that point I slowed it down and idled. then it got real low. (engine is now knocking a bit, not too too loud though) Got towed to the gas dock and put about 2-3 quarts of oil in and then it ran fine to the boat launch ( still a little knock). It seems to be burning oil fairly quickly but there is no evidence in the bildge.

lynnboy021 · Sep 4, 2010

Re: 4.3 Engine knocking, burning ton of oil,

sounds like piston rings

synergy141 · Sep 4, 2010

Re: 4.3 Engine knocking, burning ton of oil,

so what can I do to fix that?

synergy141 · Sep 4, 2010

Re: 4.3 Engine knocking, burning ton of oil,

It sounds just like this....

http://www.youtube.com/watch?v=UUtzLsWf-b8

lynnboy021 · Sep 4, 2010

Re: 4.3 Engine knocking, burning ton of oil,

first you have to run the motor for like 5 mins then turn it off then take out your oil dipstick out and look to see if it looks like a milk shake if not then your head gasket is ok... now start the motor up and see if you have blue smoke coming out the outdrive.... if you do then we an say its your oil rings or your valve seats i think its called will need o be replaced

lynnboy021 · Sep 4, 2010

Re: 4.3 Engine knocking, burning ton of oil,

is that noise coming from top or buttom??

Alpheus · Sep 5, 2010

Re: 4.3 Engine knocking, burning ton of oil,

lynnboy021 said:
first you have to run the motor for like 5 mins then turn it off then take out your oil dipstick out and look to see if it looks like a milk shake if not then your head gasket is ok... now start the motor up and see if you have blue smoke coming out the outdrive.... if you do then we an say its your oil rings or your valve seats i think its called will need o be replaced

So you want him to run his engine without ever checking his oil first? Don't you think he ran it enough to fill his oil pan with water already? Milkshakes do not automatically mean blown head gasket.

Who rebuilt the engine? I found an engine rebuilt and the guy lined up every single ring gap. Find out where the oil is going. Check for leaks, look at your spark plugs look for signs of oil burning. Perform a compression check and leak down check look for weak cylinder...

synergy141 · Sep 5, 2010

Re: 4.3 Engine knocking, burning ton of oil,

lynnboy021 said:
first you have to run the motor for like 5 mins then turn it off then take out your oil dipstick out and look to see if it looks like a milk shake if not then your head gasket is ok... now start the motor up and see if you have blue smoke coming out the outdrive.... if you do then we an say its your oil rings or your valve seats i think its called will need o be replaced

No signs of water in the oil at all.

Joshua Nichols · Sep 5, 2010

Re: 4.3 Engine knocking, burning ton of oil,

Like said before.. Do a leak down test and a compression test.. Very easy and will tell alot about the condition of the engine.. Some ol shade tree mechanic who didn't have a clue what he was doing, very well could have not staggered the rings when installing the pistons.. It has happened before... Good luck..

Aloysius · Sep 5, 2010

Re: 4.3 Engine knocking, burning ton of oil,

compression ring gap has nothing to do with oil consumption, and leak down test is not an indication of oil control. "Rings" perform 2 totally unrelated functions.

Sounds like a simple case of either really lousy rebuild or worn out engine. In any case, the solution is new or properly rebuilt engine..there ain't no "rebuild in a can".

Oil pressure is directly related to main bearing condition, and to a lesser extent rod bearing condition. A drop in oil pressure with temperature usually indicates a bearing problem.

Alpheus · Sep 5, 2010

Re: 4.3 Engine knocking, burning ton of oil,

compression ring gap has nothing to do with oil consumption, and leak down test is not an indication of oil control. "Rings" perform 2 totally unrelated functions.

Did you just make that up?

I think you need to do a little more research before making such a statement because that is totally false...

You can put a lawn mower engine together and if you line up all the ring gaps, shes gonna burn oil as well as have low compression...

A drop in oil pressure with temperature usually indicates a bearing problem.

True.

But the symptoms he is describing are it just ran out of oil. He stated that he had to put in 2-3 quarts and the noise dropped.

To the OP.

You mentioned that the engine had 10 hours on it from a fresh rebuild.

How many hours have you put on it and when was the last time you added oil?

Was the engine still running on its break in oil?

Did you check the oil before you went out that day?

If you have been running it for awhile and not checking the oil that might be your problem. New engines use a little more oil than normal until the rings are properly seated.

Having said that because you ran it for so long with no to very low oil pressure that the damage has already been done hence the "knock" is still there after adding the oil...

synergy141 · Sep 5, 2010

Re: 4.3 Engine knocking, burning ton of oil,

Alpheus said:
To the OP.

You mentioned that the engine had 10 hours on it from a fresh rebuild.

How many hours have you put on it and when was the last time you added oil?

Was the engine still running on its break in oil?

Did you check the oil before you went out that day?

If you have been running it for awhile and not checking the oil that might be your problem. New engines use a little more oil than normal until the rings are properly seated.

Having said that because you ran it for so long with no to very low oil pressure that the damage has already been done hence the "knock" is still there after adding the oil...

The person who I bought it off of "Claims" there were 10 hours on the engine after rebuild sometime last sping. It was the first time I took out the boat since I bought it. I checked the oil right before I started the engine and left the dock it was at the normal level. I ran the engine for about 30 min at 3000rpm I noticed the oil pressure dipping slowly so I kept watching it til the point I felt uncomfortable and put it down to idle and shut it down.

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dingdongs · Sep 5, 2010

Re: 4.3 Engine knocking, burning ton of oil,

pull the plugs and see if any look blackened.may be able to isolate it down to one of the pots.a ring may have broke and scored the bore(guess) but a compression test on all cylinders may hi-light condition of the rebuild.get back to us all with some figures first.

Aloysius · Sep 5, 2010

Re: 4.3 Engine knocking, burning ton of oil,

Alpheus: I beg your pardon? Ever had an engine apart? Ever build an engine and leave the second ring out? gotta clue?

"Lining up the end gaps" is a non-issue..the rings spin in their lands. Why do you think they usedta "pin" the rings. Properly fitted, the end gap is nominal..at operating temperature, the gap should be 0.005 0r less. I've run "total seals" as well as standard and dykes rings.

Oil rings provide a specific function..oil control. Period. One piece or 3 piece, they perform the same. The top ring provides compression sealing. Period. The second ring is along for the ride, and is usually a "scraper"..that's why they're often tapered.

The oil consumption mentioned is excessive. Too much rod bearing clearance, or rod side clearance, will allow the rods to sling an overwhelming amount of oil onto the cylinder walls, and get past the oil control ring. Alot of oil can go down the valve guides if they're worn and the umbrellas or o-rings are toast.

a70eliminator · Sep 5, 2010

Re: 4.3 Engine knocking, burning ton of oil,

My first thought was it sounds like the compression leak of a blown head gasket, then maybe a loose rocker arm. The oil pressure dropping after warm up is completely normal and dropping to 20lbs or so at idle while hot is what I'm used to seeing. A compression chack as mentioned earlier would reveal anything serious. Are you 100% sure of the oil level change? My oil level will read completely different with the boat floating than it does on the trailer, it also takes 10 mins or so after shutdown for the oil to drainback, you can't just shut down and check the oil immediately, it won't be accurate.

scoflaw · Sep 5, 2010

Re: 4.3 Engine knocking, burning ton of oil,

2nd ring along for the ride. Your joking right? You got the scraper thing right about #2. This IS the oil control ring, scraping back the oil in the direction of the crankcase. The 3 peice, very low tension, oil ring is what holds the oil, like a sponge to lube the cylinder wall.

Aloysius · Sep 5, 2010

Re: 4.3 Engine knocking, burning ton of oil,

Uh, no. There are more and more 2 ring set-ups showing up. We've run racing engines without the second ring..good power, but when the throttle is closed, oil is drawn up past the oil control ring. however, you can't run a 4 stroke without a good oil control ring. The slots in the pistons allow oil to return to the crankcase..the oil supply to the walls is from oil slinging off the crankshaft.

The point is..there's no relationship between oil consumption and blow-by.

scoflaw · Sep 5, 2010

Re: 4.3 Engine knocking, burning ton of oil,

Beg to differ. What manufacturer is making a 2 ring 4 stroke piston? From your own personel test you can see that the 3rd ring is not an oil control ring. Thats why it was blowing oil. Oil consumption and blowby ARE directly related. Blowby is compression getting by the rings into the crankcase. So if the rings are worn to that point, oil can travel the opposite direction into the combustion chamber. Sounds like your a 2 stroke guy.

Aloysius · Sep 5, 2010

Re: 4.3 Engine knocking, burning ton of oil,

There are diesels that are 2 ring units.

Of course the 3rd ring is the oil control ring. The only "oil control ring".

Our "personal test" showed high manifold vacuum sucked oil up. We had outstanding compression with no leakage past the ring. Dykes ring, which collapsed without pressure to seal it. Had we used a conventional top compression ring, results would have been different.

There's no relationship between oil consumption and compression leakdown. Two different rings performing 2 different functions.

And no, I'm a 2 stroke fan.

synergy141 · Sep 5, 2010

Re: 4.3 Engine knocking, burning ton of oil,

I pulled out eveery spark plug and they all look the exact same, they are a bit sooty (black) with just a tiny bit of oil on the threads

4.3 Engine knocking, burning ton of oil,

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