electrical1

Is There Anyone Who Has Installed New Gm 454 Ho Motors And Had Any Problem With Them. I Had A Mechanic Install 2 New Motors, 20 Minutes Into The First Ride, We Blew One And The Other One Started Ticking. Had Local Machine Shop Look At Motor And 2 Pistons Where Destroyed Inside. Machine Shop Thinks Tolerance Where To Tight. Installed Another New Motor And 10 Minutes Later That One Blew. These Are Brand New Crate Gm 454 Ho's Long Blocks. What Is Happening Here Could They Be Bad Motors Or Are We Doing Something Wrong. I'm Running Fresh Water Cooling, And Brand New Holley 800's Was Running 750's First. Any Advice

electrical1

By The Way These Are Installed In A 42' Wellcraft Excalibur Eagle With Trs Drives. New Elbrock Rpm Intakes

Vinny P

I don't mean to insult you but I saw this a few weeks ago. I went to check out a blown-up v-6 motor for a guy. This was a new motor that lasted only a few hours. It seems that the ( mechanic ) that did the install never bothered to clean out the oil cooler. The debris from the cooler got into the new motor and boooom.

paradigm shift

Yea a marine motor is cleareanced a lttile more on the pistons. Marine motors run under heavy load most if not all the time. Are you sure the timing was on and motors did not detonate them selves to death? Any pictures of pistons and bores might help. What did the plugs look like? Not sure about the 454ho but I know of a few 502 GM crate motors that have worked out well with no tear down prior to install. Not much help sorry.

offthefront

iTrader: (1)

Are you saying it would or is a normal practice to open a crate motor and check things out before a new install ?? Might make sense

electrical1

Plugs Look Good Not White From Lack Of Fuel. 1 Piston Looked Like It Was All Chewed Up Like Someone Dragged It Along The Ground Till Nothing For Left. The Cooler I Don't Know About, If He Bothered To Clean It. The Orginal Motor That Was In The Boat Didn't Blow Apart It Just Seized Up Because It Ran Out Of Oil Because Of A Presure Fitting On The Remote Oil Filter, So Even If He Didn't Clean It Not Sure If There Would Be Any Debre Any Way. Both New Motors Run For A Short Time And Then Out Of The Blue One Piston Just Blows. Oil Presure And Water Temp Are All Good Until It Blows, Then Water Temp Pins High.

cig1988

That is why I never went with crate motors from GM. Have a good machinest tear a crate motor apart and you will be suprised what he will find. Nothing like an "aged" block to work from as a base. Sorry to hear about your misfortune.

HeavyChevSS

I replaced a 330/454 with one of the 502 HO's and didn't have any problems, not the exact same motor but think is same except for the displacement. You blew up (2) or damaged (1) motors in less than an hours run time? something majorly wrong there. Someone more experienced can correct me but even though in optimum conditions marine engines are built with different clearances I don't think the run of the mill Mercruiser stuff has been changed- they for the most part are the same as the GM crate stuff. What did the installing mechanic have to say about it?
Good Luck,
Rich

articfriends

iTrader: (1)

As far as i know the 502 ho/454 ho are IDENTICAL to the 454 mag/502 mag long blocks before the external parts are bolted on. They were made on the same assembly line with the same exact pistons,rings,gaskets,CLEARENCES,down to even the part #'s. Until you stepped up to the hp 500(which mercury racing hand builds with select high dollar parts,not mercruiser) thats what you get. A member posted that they use different cams a few days ago but mercruiser doesn't buy them then blueprint them or clearence them. I have the original 2000 502 mag in my shop dissasembled and other than the posibility that the cam is smaller (i never measured the duration on it and lift)it is IDENTICAL to a crate 502 ho we freshend for a friends street rod.If electrical1 had 2 failures after such a short run time he needs to find the cause of his failures (external bolt on parts-cooling system,oiling system etc)or really had bad luck!Smitty

electrical1

The Only External Parts You Reuse Is The Carburator, Distributor, And Oil Cooler, Every Thing Else Comes With The Long Block Or Are New The Plugs Are New (differnet Set With Each Motor That Blew)the Oil Filter Is New The Carburators Are New ( On Second Replacement, Went From 750 Holleys To 800 Holleys Because Someone Said That The 750's Where Wrong, But Found Out Later This Was Not True That Was A 1200.00 Waste Of Money). Had A Professional Machine That Builts Racing Motors Look At The First One, They Felt It Was A Internal Clearance Problem. Each Time Its Only 1 Piston That Goes Bad The Bottom End Looks Excellent And The Rest Of The Pistons Look Like New. Was Just Wondering If There Where Any Known Problems With These Motors. Don't Know Where To Turn At This Point. The Season Is Ruined Now. Its To Short Here On The East Coast.