3l volvo impeller self-destructed, brief overheat, now runs rough - why

[bwoodone]

1998 volvo 3.0 carb - was running well then impeller self-destructed and it briefly overheated. Got new impeller but now its hard to start (must WOT to get it going) and it runs rough - any idea why? are there things I should check

 

[Maclin]

Re: 3l volvo impeller self-destructed, brief overheat, now runs rough - why

Compression check. May not have been as "brief" to the engine, head could have warped and then the gasket blew out.

 

[bwoodone]

Re: 3l volvo impeller self-destructed, brief overheat, now runs rough - why

what shud compression number be? if not, what do ya do; shave head and get new gasket? thx for help

 

[Don S]

Re: 3l volvo impeller self-destructed, brief overheat, now runs rough - why

I would be several things happened with the overheat. When you noticed it, you probably shut it down immediatly, and it dieseled like crazy until it finally stopped. During that process, the usually suck in a lot of gas, and a little water in the process (from the exhaust).
Then when you finally got it started at WOT (that's how you clear a flooded condition) the little bit of water probably have a plug or two fouled.
Pull the spark plugs, crank the engine over and make sure there isn't any water, do your compression check. Clean and dry or replace the plugs and see how it runs.

 

[bwoodone]

Re: 3l volvo impeller self-destructed, brief overheat, now runs rough - why

Hi. After I got it back from the impeller replacement I cleaned all the plugs and litely sandpapered rotor and inside the cap. There was some suit. I Had to WOT start it cuz it was sputter firing - almost starting but not quite. It ran OK but when it got hot it was intermittently running rough. I gave the port side carb adjustment about 1/2 turn clockwise and it smoothed out. Then I gave it a hard run, shut it down and tried to re-start, it didnt go right away and the starter went. So this wknd after I get a new starter in - what would you suggest to do? Compression test?

 

[bruceb58]

Re: 3l volvo impeller self-destructed, brief overheat, now runs rough - why

yes...compression test. And when you get that done replace your cap, rotor and plugs. Sanding the cap and rotor is usually a big waste of time along with cleaning plugs.

 

[Maclin]

Re: 3l volvo impeller self-destructed, brief overheat, now runs rough - why

"...I gave the port side carb adjustment about 1/2 turn clockwise and it smoothed out."
Overheating would not knock a carb out of adjustment, just sayin'...

"...Then I gave it a hard run, shut it down and tried to re-start, it didnt go right away and the starter went."
That sounds like hydrolock. Have you removed the sparkplugs since this?

 

[bwoodone]

Re: 3l volvo impeller self-destructed, brief overheat, now runs rough - why

I hadn't read this and went ahead and replaced the starter. The new starter worked to start the boat about 10 times, then the new starter went. Same symptoms as the one replaced - grindy noises, then the starter drive went - and when U turn the key it just whirrs like a dremil tool.

I examined the ring gear - its fine. So now I have another starter to put in there - do I need to do other things before installing it to address the hydrolock (can U explain what this is) to avoid destroying this starter too? For sure I can remove the plugs first.

Thanks - I'm kindov nervous about this. Do I maybe need to shim these replacment starters so they engage properly or????

 

[Maclin]

Re: 3l volvo impeller self-destructed, brief overheat, now runs rough - why

If the engine turned over then it was not hydro-locked. I was trying to help you prevent damage to the engine in the event any cylinders had ingested water.

Hydro-lock ocurs when the engine gets water in one or more cylinders thru an open exhaust valve when it is off or right when it turns off. The water can come in from a compromised exhaust manifold or riser or riser joint. It can also get in if the engine runs-on after it is shut off. Then the next time the engine is cranked the water will not compress and the engine will not turn once the cylinder(s) with the water hits the compression stroke. If the starter is strong enough or if the engine tries to catch just before the lock occurs it can bend a rod.

I wish I knew more about the starter, I am sure others will chime in soon.