151 threw a rod!!

[rthomas]

it went clang and bang and now has a hole the size of a 2x4 in the block, my question is can i use an automotive block? are the cranks different? i know the heads are ported differently but i think mine is still good. thanks, russ

 

[Coors]

Re: 151 threw a rod!!

Marine blocks are automotive, but with brass core plugs, and basically a truck cam.
Heads are the same.

 

[Coors]

Re: 151 threw a rod!!

But why did it throw a rod? Oil pressure? Old? Over -reved?

 

[Silvertip]

Re: 151 threw a rod!!

Possibly all of those reasons. What was the oil pressure? Did it have sufficient oil. Did it overheat? Did it begin knocking before it went "bang"? What RPM were you running at? When running at wide open throttle, what were the RPMs normally? Was there water in the oil (as in a chocolate milky appearance). Tell us the truth!!

 

[bomar76]

Re: 151 threw a rod!!

deleted

 

[Coors]

Re: 151 threw a rod!!

lol; we want the truth

 

[rthomas]

Re: 151 threw a rod!!

i was messing with the timing, it was pinging and had low power and i assumed i was having problems with the pertonics unit so i was messing with the dist. quite a bit and i thought i was getting somewhere it wasnt pinging and had almost normal power, so i pushed the throttle up and it went bang at about 4800. i guess i had a mechanical problem and completely mis read it as an ignition problem. the oil pressure in this motor has always been 80 at rpm 60 at idle and uses almost nothing

 

[chiefalen]

Re: 151 threw a rod!!

151 is a 2.5l chevy marine engine you could go to a 3.0 chevy engine i would if i were in your position look on ebay and get one.3.0 would give you 15-20 more horse power.

 

[Silvertip]

Re: 151 threw a rod!!

Thanks for telling us the truth. Lots of times we never know so threads get verrrrrry long until all once the poster spills the beans. Threads like that could be much shorter. In your case, messing with the timing is likely the cause of the failure. Too much ignition timing and high revs will grenade an engine. Lesson learned -- use a timing light and a service manual. 60-80 PSI oil pressure does not cause rod failure.

 

[rthomas]

Re: 151 threw a rod!!

after eyeballing it a little i think i slipped the timing belt a tooth, and that fits everything it was doing before it grenaded, i wish i had thought about that before it went bang. i just rebuilt the carbs and had the head done, hopefully thats salvagable

 

[Don S]

Re: 151 threw a rod!!

The AQ151 Volvo Penta engine is NOT the Chevy 151. It's an overhead cam VP engine all the way thru.
It is also a non interference engine, in other words, even if the timing belt fell off at 5000 rpm, the pistons will not hit the valves. So that did not cause the engine to blow a rod. OF course detonation and pre-igniton could melt a piston, but break a rod? I don't think so.
Probably just a material failure (metal fatique)