7.4MPI oil loss... wheres it all going?!?!?!

A qt. an hour at 3800 is excessive for sure, but if it runs good, oil is cheap and it is summer.
 
A qt. an hour at 3800 is excessive for sure, but if it runs good, oil is cheap and it is summer.

honestly thats kinda where i am with it at this point, i'll worry about it more once i pull the heads off to get the tops ends done.
 
could be for sure. more than likely i'll just pull the motor and go over the entire thing when it comes that time. my motor builder has 2 motors for my race car currently so it will be after those are done lol
 
My Crusader 454s were rebuilt 4 years ago with new cast pistons (.010 over), bearings, lifters, valves, mild performance camshaft, rockers and Melling oil pump. They now have about 180 hours and they have yet to consume oil. I'm a bit surprised at the oil consumption numbers being quoted here.
 
My Crusader 454s were rebuilt 4 years ago with new cast pistons (.010 over), bearings, lifters, valves, mild performance camshaft, rockers and Melling oil pump. They now have about 180 hours and they have yet to consume oil. I'm a bit surprised at the oil consumption numbers being quoted here.

Good engines, but completely different brand...

MM
 
updates... well... kinda

ran out the rest of the season... STILL no idea where the oil is going.
 
Strange problem.

My 1998 7.4 MPI went 105 hours last season and didn't even use 1 full quart of oil. She's got almost 800 hours on the motor and I cruise around 4000r's.

FWIW, I use Brad Penn high zinc racing oil
 
Out the tailpipe. It's not in the bilge and you replaced the oil cooler right ? Thought you were gonna rering this thing after your machine shop finished building your race engines.
 
My bet it’s all blow-by. If cruise is 70% of WOT then you should be closer to 3200-3300 rpm on 7.4?

I had 7.4 mercruiser w visible blow-by when pulling oil cap but it didn’t consume anywhere near what your getting.

It rings.
 
updates... well... kinda

ran out the rest of the season... STILL no idea where the oil is going.

Don’t know if my info will help, but...I bought a used 1995 Dodge p/u with the 318 years ago. Drove it normal for a few weeks no problem. No leaks. No smoke. No oil consumption. Towed my 4500 lb boat about 100 miles and my oil light came on. Fast forward a few weeks: the Oil Pan Gasket had blown out. It lies between the intake manifold and block. Under a load, the increased vacuum sucked oil directly from the pan and blew it out the exhaust. Normal driving did not create enough vacuum. The oil did not burn. No engine drips. It went right out the exhaust pipe. $1 gasket took a removal of the intake to fix. I am not sure if that engine is anything like yours. If you pulled an exhaust manifold and studied the inside of the exhaust, you may find clean oil.
 
Oil cooler leaking inside??? Greater oil pressure than raw water pressure allows oil to leak out but not let water in.

Just a thought -
I did not read entire thread ,just in case someone already mentioned.
 
Out the tailpipe. It's not in the bilge and you replaced the oil cooler right ? Thought you were gonna rering this thing after your machine shop finished building your race engines.
yes oil cooler was replaced... he finished my 408 he still has my 393, his back log would probably be next winter before he got to it.
talking to buddy of mine who is a boat mechanic we might just get a jasper rebuild and do that one weekend. he needs to get prices on a 454 and 502's for me still and go from there.
 
make sure you run that new engine on the floor before you install it! I have seen bad ones from them right out of the box.
 

Forum statistics

Threads
112,945
Messages
1,422,754
Members
60,928
Latest member
rkaleda
Back
Top