Which oil pump when rebuilding a 454
 

Hey guys I'm replacing the screen on my oil pump because I'm convinced that it is built up with sludge and losing pressure after about 20 minutes. I figured while it is out I might as well replace the pump since I am there. The guys at the local boat shop said to not use a High pressure/volume pump, but to use a Heavy Duty (never heard of one). I can't find a heavy duty pump for the 454. So I called the guy who has done some motor work for me in the past and he suggested a M77HV which is a high volume standard pressure pump.
Any input would be great.
Don't know if it matters but it is in a 89 IMP Eleganza 310

Fixx
 

melling,,10778c its worth the extra 30 bucks..make sure you replace the pick up tube also and it needs to be tack welded on so it dont fall off while pounding waves..

I guess another question I have is with the high volume (these list at 25% over stock) I wont have an issue with the stock pan? Some people say you need at least a 12 quart pan (which seems like a little much). I like the idea of that anti-cavitation pump and I get a good deal on parts, I'll probably spring for that as long as there is no issues running the stock pan with a HV pump.

Stock pan, big oil cooler, holds steady at 70psi

What exactly is leading you to believe the screen is built up with sludge? And, if that's the case, why would the engine take 20 minutes to lose oil pressure?

How much oil pressure does it lose?

To answer your original question, I wouldn't bother with a HV pump in a stock pan. If the engine is stock, there's nothing to be gained by using a HV pump.

Fixx
 

use the pump number i gave you,,if it comes with another spring read the directiond and it will give you lower pressure so you dont suck the oil pan dry.

Oil pressure will always drop some from when it's cold to when it gets hot. Seriously doubt there is any sludge what so ever on the pick up screen. HV pump is totally unnecessary on a stock engine. All it will do is use more power from the engine to turn it.

some good thoughts posted above about your analysis ... " why 20 minutes ?" and " loses press cold to hot " and i think you need to look around a bit before you jump to conclusions and have to do a lot of work again...

first thing to ask and report is how it used to be... is this a new problem, sudden problem, never did it before, always did it before , oile temps bef and now etc... those answers tell you a lot about what's really happening... but beyond that even, what are the critical numbers ? cold idle, hot idle , cold 3500 rpm, hot 3500 rpm.

lets assume that you have a real issue... press used to be normal, now they aren't and temps are ok... you think you have sludge... well that's unlikely but its as good a guess as any and assuming you have done all the normal external things first, lets say you have the pan off... what do you find ? is there an inch of sludge in the bottom of the pan ? well ... if there IS then you need to seriously consider having a look at the rod and main bearings while you are there for obvious reasons... and the top end of that motor isn't going to be a joy to look at either ...( and how did you let it get like that ?)

as for oil pumps... don't reinvent the wheel. the oil pump and specs that it came with did the job just fine for a long time and was designed for the clearences and bleed rate that your motor has. hi vol oil pumps and all the rest aren't cures for anything that isn't broken and since you aren't changing the basic archetecture of your motor , you don't have anything to fix in that regard. put stock specification right back in.

and someone please explain to me this whole " suck the pan dry" routine... where do you think the oil goes and hides ? it comes out of the pan, thru the pump, into the galleries, thru the bearings and back into the pan... if its too much it bypasses ... into the pan.

there is nowhere to hide 500 cubic inshes of oil unless every drain back from the top end is sludged solid as well... and if thats the case then no band aid oil pump or oil pan is going to fix any of this...

All good questions raised, and I'll add one more - loosing pressure after 20 minutes of running could be an oil cooler problem. The stock oil cooler is sized for nothing more than a stock engine - adding power, etc will overheat the oil. On mine, the PO put in a 160* water t-stat, and I was seeing oil pressure drop after 5 minutes of WOT. Check of oil temp showed it was reaching 280* oil temp. Changed to the specified 140* t-stat, and problem solved. I'd check all the folks above pointed plus the cooler function and water temp before changing anything.

I run a 160 t-stat which is what the MPI calls for. Its a 89 block with 300 hours, and I put a fresh set of '98 heads on it with a Merc MPI setup.
before I bought it the motor sat for 2+ years with used oil so I'm thinking that it clogged the pickup enough to supply sufficient flow at lower RPM's and for short periods of time at higher RPMS.
I had the oil cooler pressure checked before the engine was installed and was told it was alright.
cold idle psi is about 30, 1k is about 40.
I can run it all day at 3k and have it hold 30psi + or - a little. Its when I run it to WOT that it spikes at about 45 and starts to drop slowly after about 10 minutes. If it's the mains and rods then I waste a day of my time pulling the motor and replacing a 70$ melling pump. My season only has about 6-8 weeks left I'll see what happens.

well... this is all educated guesswork , of course... but ...

the cold pressures sound close but 40-45 is low cold... and what you describe after some time at hi revs sounds a lot like an oil temp deal.. either the temp is very high or the clearences are such that even when the oil is at 210 it is now too thin for the clearences... and i suspect this because of the low cold pressures. now all this is predicated on your gage being correct and all the normal stuff. engines don't make sludge by sitting. so i think you are wrong about that. i don't think its a supply issue at all. if i was standing where you are i would do the following: change the oil and the filter to a straight 30 oil... any name brand. i would cut open the old filter and see whats in in it. i would sniff the old oil to see if it smells burned or full of fuel. i would have the oil cooler off and make sure the water passages are clear. and i would put a mechanical gage on it that i could just drape the line up to where i could see it when i was driving the boat and try it all again. if , in fact, it really does start dropping pressure as you say when it gets hot and that would mean that when it idled hot it would be at about 5 or 10 lbs, then you have some sort of bottom end problem. bad mains probably... but if the pressure fall off hot at speed but still idle at 25 or 30, hot then thats going to be something else... something unusual...

i wonder if the relief valve got rusty and isn't sealing up well... or something simple like that... but at anyrate... spend some time and do some simple straightforward diagnostics and then go where the data sends you...

I just pulled one of my motors down because of a loss of oil pressure. Mine would start up and be a solid 40 pounds, after about 10 - 20 minutes of solid running, pull back to an idle it would drop to 10 - 15 then if it idled down to 500 rpm it would drop on down. Pulled motor apart and found #2 main bearing spun. No noises no loss of power. Hope this will help you.

Sounds very close to what mine did when the oil got hot. Only difference is the pressures, yours look low to me. I'd follow Stevesxm's plan, but if you can get an infrared temp indicator, I'd check the temp of the oil filter when running WFO as a proxy for oil temp. the filter casing surface will be 10-20* low, but it will give you an idea where your oil temp sits. Obviously, you'll need a friend to do this. Or get an oil temp guage.

Interesting thread since I just had a newly built 454 lock up on me...it would run good oil pressure until a hard run and when throttled down it would drop very low. Am curious about the comment on a spun bearing...someone has suggested that I could have had a spun bearing and then the crank broke. Techs taking it apart next week or so to see what went wrong. If this is it, how exactly do you keep it from happening?

well.. it sounds like a wise ass answer but the truth is that if the motor is assembled competantly from parts that are correctly measured and correct for the task then thats all you need to do.
100 out of 100 times when fresh motors fail it's because someone screwed up along the way. now... it's easy to say " gee the machine shop screwed up the crank sizes so it blew up" but ultimately and absolutely and without exception it is the responsibilty of the guy putting the parts together to make sure everything is the correct size and configuration before its installed. the buck stops there. if you can't measure bearing clearences and are relying on someone else to tell you its ok for you to put together then you are not qualified to be doing the work. and when it blows up you have absolutely no one to blame but yourself. nothing happens by accident. if you put all the right parts in all the right places in the right manner then you don't have these issues.

there are no exceptions... certainly you take calculated risks along the way. if you have a perfectly good running motor and it needs freshening, then you don't send the block out for e xray or magnaflux... you assume its not going to be cracked when you are done because you know it wasn't cracked when you started... and if you are wrong and in 10 hours it does crack you shrug your shoulders and say " oh well" ... its still your fault but you made a rational decision based on sound information. but if you get a motor out of a junk yard thats been sitting in the snow for two years and don't crack check it then you are dumb... and everything elses is something between those two extremes.

There's a whole lotta truth right there... Every word of it. :drink:

:flag:I had some low oil pressure issues just recently.The engines were fine in the the last season.This year started to show both engines dropping in pressure.Long story short.Check your electric connections.I cleaned mine and now I have normal oil pressure.Resistence on the wires wire will lower the oil pressure indication on electric gauges.

thats correct. thats why every oil pressure related thread always has " put a mechanical gage on it and confirm the numbers" in it somewhere. just like this one...

" i would have the oil cooler off and make sure the water passages are clear. and i would put a mechanical gage on it that i could just drape the line up to where i could see it when i was driving the boat and try it all again. if , in fact, it really does start dropping pressure as you say when it gets hot and that would "

The best oil pump is the OE pump at the local Chevy dealer. I suggest buying the Mark IV pump that has the pick-up tube welded in place already. Not sure of the part number but I believe it is GM # 3969870. They are not much more expensive than the Mellings but of higher quality. There is a difference between the OE Pumps.
The Mark IV pump will not fit on a Gen IV or Gen V main cap because of taller main cap bolt bosses. Take yours to the dealer and compare.
Dennis

Also, you mentioned the guys at the local boat shop talk about the "Heavy Duty" oil pump.

GM calls the #3969870 oil pump the "Heavy Duty" oil pump.

Dennis

Also, you mentioned the guys at the local boat shop talk about the "Heavy Duty" oil pump.

GM calls the #3969870 oil pump the "Heavy Duty" oil pump.

Dennis

fixx
 

I guess you never used a 10778c melling pump..I bet if you saw how much better it was made you would change your mind..

fixx
 

that pump #says race only??? have you used them and how many hrs are on the ones in your engines. dont mind spending the extra $$ but i also want to kn ow this thing will go the distance

No Brainer!
 

We have built many engines in our shop in the last 10 years and the 10778 series Melling Select oil pumps are the only ones we use. NO Problems, No Failures and NO Unhappy Customers, take it for what its worth use that pump!

Best Regards,
Ray @ Raylar

fixx
 

they work awsome and no failures.. no? ray has the perfect answer

Bringing this back. I'm building a 496 stroker with stock oil pan (Gen V) and windage tray. Would the melling 10778 be appropriate for said application? No I don't want a aftermarket 14 quart pan and I'm using a large oil cooler. Thx