Little help if possible
#1
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Little help if possible
I have a 1998 5.7 vortec motor (that has had the block swapped for a 383 stroker. ) and i am having a power loss issue. Once up on plane with no issue i can hold her there for a few minutes then she looses power (probably 40%) and at the same time the alarm sounds. Its a 4 bbl carb motor (changed from 2 bbl when sroker block installed). All guages read fine. I also just discovered that my oil dipstick was spitting oil out of the top pretty bad. Can a loss of crankcase pressure cause such a loss of power and also set off an alarm. Oil pressure stays at around 40 all day.
any insight greatly appreciated.
Thanks
Brian
any insight greatly appreciated.
Thanks
Brian
#3
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Sounded like fuel psi at first, and then read the oil out the dipstick deal.
Assuming it has the stock Merc crank breather set up on the vc's, then I would say check compression. Sounds like the motor may have a ring/piston sealing issue.
You have the classic symptoms of such, so again, ck your compression.
Assuming it has the stock Merc crank breather set up on the vc's, then I would say check compression. Sounds like the motor may have a ring/piston sealing issue.
You have the classic symptoms of such, so again, ck your compression.
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Compression is good. 180 - 185 in most. Two fronts a little closer to 190. There's probably only 150 hours since new stroker block so internals should be good.... I also thought about fuel... got 5 to 7 psi steady. Its a single electric fuel pump running right up to a split line for a holly 4 bbl carb. I know on the big efi motors you need like 45 psi at the rail but on this motor I assume 5 to 7 is ok?. And cant see how low fuel pressure to trigger an alarm... I was under impression only overheat, low oil pressure or low gear oil could trigger alarm. I see this engine has sort of half a computer (early days of ecm i guess) can that thing throw codes? I learned on newer stuff like 7.4 MPI and up where you can connect a reader but didn't see a port on this one.
thanks so much for responses guys i really appreciate it!
Brian
thanks so much for responses guys i really appreciate it!
Brian
Last edited by Plaineman; 09-28-2014 at 08:14 PM.