Volvo Penta 5.0 GL will crank, but won't run after overheat

[Mzeller98]

I have a 1998 Volvo Penta 5.0 GL. Lost the impeller over the weekend and it overheated. I don't think it was too bad of an overheat, but I shut it down, and was towed back to the dock.

Checked oil, and it doesn't appear that it has any water. Boat wouldn't crank, so thought it may be hydro locked. I removed plugs, cranked it, sprayed some WD40 in the plug holes, cranked, it, etc. to try and get out any water that may have come in during the overheat. There was moisture in the plug holes, but it wasn't soaking wet by any means.

I replaced plugs and was able to get it to fire, but not stay running. I've tried everything I can think of, but it will not stay running. It does fire up, but then dies. Feels like it isn't getting fuel. I checked the fuel pump relay thinking maybe alternator isn't taking over once it cranks (per other post. I have correct voltage from 30 and 86, and jumped 30 to 87 to try and eliminate the alternator from the equation. Same result. It will crank and rev for a sec, and then feels like it is out of gas.

Any suggestions on next steps? I was set to tow the boat 1200 miles on Friday and leave it for a family retreat..

 

[Mzeller98]

I have a 1998 Volvo Penta 5.0 GL. Lost the impeller over the weekend and it overheated. I don't think it was too bad of an overheat, but I shut it down, and was towed back to the dock.

Checked oil, and it doesn't appear that it has any water. Boat wouldn't crank, so thought it may be hydro locked. I removed plugs, cranked it, sprayed some WD40 in the plug holes, cranked, it, etc. to try and get out any water that may have come in during the overheat. There was moisture in the plug holes, but it wasn't soaking wet by any means.

I replaced plugs and was able to get it to fire, but not stay running. I've tried everything I can think of, but it will not stay running. It does fire up, but then dies. Feels like it isn't getting fuel. I checked the fuel pump relay thinking maybe alternator isn't taking over once it cranks (per other post. I have correct voltage from 30 and 86, and jumped 30 to 87 to try and eliminate the alternator from the equation. Same result. It will crank and rev for a sec, and then feels like it is out of gas.

Any suggestions on next steps? I was set to tow the boat 1200 miles on Friday and leave it for a family retreat..

Any suggestions to test fuel pump to see if it is actually pumping enough fuel to keep the engine running? If the problem is spark, would it crank the first go around?

 

[dubs283]

Any suggestions to test fuel pump to see if it is actually pumping enough fuel to keep the engine running? If the problem is spark, would it crank the first go around?

check fuel pump pressure and check for voltage at the pump harness. possible its getting voltage during cranking but oil pressure switch/wiring may be faulty/melted from overheat

check for spark with a spark tester at the coil/plug wire ends

 

[Mzeller98]

check fuel pump pressure and check for voltage at the pump harness. possible its getting voltage during cranking but oil pressure switch/wiring may be faulty/melted from overheat

check for spark with a spark tester at the coil/plug wire ends

Turns out it was a loose connection at the kill switch. Must have gotten hit during the overheat commotion. I thought that killed all spark to coil so was surprised it would fire the first time. Anyways, once I reset the kill switch, it fired right up. That revealed more problems once I got it running….

Installed new impeller, and ran it on muffs for a bit and it was great. Almost declared victory. Drained oil and it was clear water was present. Changed oil, and tried to start again and it wouldn’t turn over. Pulled plugs again and a lot of water was present in several of the plug holes.

From what I’ve read from this forum (which is awesome btw,) I think it means either gasket failure on manifolds/risers, head gasket failure, and/or cracked engine block. I have no idea how to narrow it down.

Is next step compression test? If that is ok, does that rule out head gasket and engine block and point to manifolds/risers? If it isn’t ok, is there a way to narrow down between head gasket failure and cracked block?

Thanks so much for the help.

 

[Backyardmech]

It is most likely 1 or both blown head gaskets. 5.0 gl is iron block and heads normally an overheat wont crack anything (but it is possible). Head set will cost a few hundred dollers and isnt too hard to do yourself if you know how to use a torque wrench.

 

[Mzeller98]

It is most likely 1 or both blown head gaskets. 5.0 gl is iron block and heads normally an overheat wont crack anything (but it is possible). Head set will cost a few hundred dollers and isnt too hard to do yourself if you know how to use a torque wrench.

I'll venture to replace the head gaskets. Any step by step instructions on what/how to remove everything to get to the gasket?

 

[Backyardmech]

It would be best to look up a video on head gasket replacement. You need to remove both exhaust risers and manifolds, distributor(dont forget to mark the plug wires and rotor orientation before removal), carb and intake manifold, alternator, power steering pump, water pump, fuel pump bracket, valve covers, loosen rocker arms, mark and remove push rods finally remove the head bolts(there are usually 2 lengths of head bolt and they are not interchangeable). When disassembling an engine i like to place the nuts, bolts, retainers from each step in a zip lock bag and label it as well as take pictures of wiring harnesses and vacuum lines for later reference.