Bronco Forum - Full Size Ford Bronco Forum banner

1 - 20 of 20 Posts

·
Registered
Joined
·
3,423 Posts
Discussion Starter #1
blew the motor... lost either a main bearing or rod bearing... no oil pressure...horrible knock..
oil pump works... im suspecting one of those two bearing failures... due to the two loud BANG!'s i heard

so yea... the 351 is broke...

picking up the f4 roller block tommorow... 393w build begins

build thread soon:thumbup

dc
 

·
Registered
Joined
·
2,689 Posts
Man that sucks I guess.

At least you get to build your 393 now.
 

·
Satyr of the Midwest
Joined
·
17,734 Posts
So does it still run? :toothless
 

·
Registered
Joined
·
3,423 Posts
Discussion Starter #5
ummm barely runs... it knocks so loud...like a hammer on wood. really loud... also heard two or 3 LOUD bangs from deep in the motor... prolly the bearing letting loose... like .22 cal rifle kinda loud lol

yea ive been anticipating building the 393w... just wasnt ready to start it yet

dc
 

·
Registered
Joined
·
1,394 Posts
I'm worried about that happening to mine as well... how was it running prior to your comp. problems? I need to know in advance when mine is going to blow so I can schedule around it lol:toothless
 

·
Registered
Joined
·
3,423 Posts
Discussion Starter #13
yea the motor isnt too old... however we never touched the used shortblock... it was pretty clean... im guessing poor quality bearings were used...

most likely what happened though is a small piece of gasket must have wiggled its way down to the oil pan... most likely when i pulled the lower intake off back in dec 07... yes i was very cautious and precise about that... i know everything was done right there... however a piece of baked brittle cork gasket could have fallen under the valley...

i have had a tap for sometime... however it was minimal... very slight lifter noise most likely from the crappy summit($3 each) lifters i was using...
after the new lifters went in and motor was put back together i primed the oil pump and dropped the dizzy in... fired right up... slight tap at first and then nothing...

after i finally got it running after all of this electrical mess it developed a strong lifter knock... it was loud... so i got it in the shop and after cleaning up electrical i fired it up again to see what this knock sounded like... after starting it that time i heard 2-3 loud bangs...really loud.... knock continued and got worse the higher the rpm... however i had great oil pressure according to the stock guage... yea i know it needs to go

to top this all off, the knock i was hearing actually sounded more like a exhaust leak @ the head... i also installed some thermacator plugs which i suspected to eb leaking...
so i decided f-it... dmg was done in those bangs so i ran it around the neighborhood to see if i could isolate it.. thats when the oil pressure dissapeared...

brought it home and shut it off... well it stalled lol

i drained the oil, its got some metal in it... kinda thick metally soup...still black not grey...but yea

anyways so i dont know if this failure was caused by:
A. A piece of something clogged the oil pump... (i tried priming the oil pump drive shaft again to day and noticed it was pretty tough to turn... it was fighting my drill some... not seized or anything... just tuff... ) i got no oil pressure reading from the guage

B. coincidentally the rod/main bearing let go during all of this mess... basically leaving a big hole in my oil system for pressure to bleed off... it sounds far fetched but it fits my luck pattern

we will know when i pull the pan

dc

ps.. hey ryan... the KB pistons your using came out to be like a 7.5 CR w/ a 60cc gt40p head on 4.00 bore... how do you plan on 9.5:1
 

·
Registered
Joined
·
3,423 Posts
Discussion Starter #14
i didnt have any issues prior to that... that oil pump was only 2 years old... they dont go bad often nomally...
yes its normally my dd...
when the oil pump went out on my 302... i suddenly lost some power due to friction in the motor... the first thing you will see though is the oil pressure guage will bottom out @ idle or a stop

it may happen to you one day lol... not really something you plan for... itd be like having an xtra rebuilt trans lieing around just incase yours goes...
keep a little pillow of cahs in the bank account if you can and keep your eyes out for good deals... i got my roller f4 block complete pan to throttle body for $250

im hard on that truck too... ive got a heavy right foot
 

·
has no skidplate
Joined
·
4,320 Posts
the first thing you will see though is the oil pressure guage will bottom out @ idle or a stop
my motor's had crap for psi since i got it
it dips to about 5psi in the summer hot, so i know it's then time to add the STP
it's wierd because i have normal psi when i start these days, but come summer i expect that to go downhill
i know it's on borrowed time, but i do what i can to extend that time
 

·
OUT OF BUSINESS / M.I.A.
Joined
·
10,858 Posts
basically leaving a big hole in my oil system for pressure to bleed off
Thats what happens. My engine had 5PSI when the old lifters were bleeding off oil. Thats when I did the roller cam upgrade.
ps.. hey ryan... the KB pistons your using came out to be like a 7.5 CR w/ a 60cc gt40p head on 4.00 bore... how do you plan on 9.5:1
You have to factor in the 3.85 stroker crank.
I use this site for CR calculations http://www.rbracing-rsr.com/compstaticcalc.html
 

·
ate lug
88 + 96 broncos, 96 F250
Joined
·
8,685 Posts
... however i had great oil pressure according to the stock guage...

Theres your mistake right there. You assumed that the stock gauge is a full sweep, but it is only an on/off gauge, reading 'normal' as long as the oil pressure is above ~5 PSI. Most likely your oil pressure was low for quite some time.
 

·
Registered
Joined
·
3,423 Posts
Discussion Starter #18
yea i understand that rept... ive just been too lazy to get the new guage in

looks like i may be picking up another vehicle... bronco can be relieved of DD status... so now ive got some time to build it

:D
 

·
Registered
Joined
·
2,066 Posts
This is what makes me scared to rebuild my first engine for my 86
 
1 - 20 of 20 Posts
Top