dead big block

[wrench]

Hi. i need some opinions on what happened to my engine. i have been having trouble with hot no starts(would restart after 1 hour or so) and some occasional surging(really felt like vapor lock) and then finally the other day it just died and wouldn't restart(cranks ok). Sooooo i removed the inlet hose to the fuel pump and connected a vacuum gauge to the pump and cranked it over(no vacuum!), disconnected the fuel line to carbs to make sure(no vacuum),removed the fuel pump(seemed ok, installed in a vise and actuated the plunger with the vacuum gauge installed and lots of vacuum(15"), lever, everything looked good. Checked the pushrod travel when cranking(about 1/4"),,is that enough travel?? Anyway cranked engine over to base circle of pump cam and trial fitted the pump back on the engine. I couldn't feel the pushrod putting pressure on the pump lever at all and with the pump having about 1/4 of free play on the lever before the diaphragm starts moving i figured the pump wasn't being pulsed by the cam eccentric..so i removed the pushrod and found it to be worn out(at least 3/16") with both ends being galled..the pump lever looks like brand new,can hardly tell anything was rubbing against it..This engine is a fresh rebuild with 500 miles..Now my question is could it be just a bad pushrod heat treatment(new mopar) or an oiling issue..i also have 3/16 of metal filings in my oil now.

[firefighter3931]

The BB pump pushrod should measure 3.25in long. If yours is shorter than that then you have a problem. It's also possible that the lobe that actuates the pushrod (on the camshaft) has gone flat. Good quality oil is critical with flat tappet cams and mechanical pumps. Lots of Zinc/Phosphorus needed to help these parts live. There's a long thread stickied to the top of this page outlining those issues.


Ron

[wrench]

Thanks ff. My pushrod measures 3" only.i am using quaker state 15/40 diesel semi synthetic oil. Is that good enough oil to use???

[elacruze]

If your fuel pump pushrod is galled on both ends, sounds like you got a stiffie on the rebuild... cam lobe was wiped and cam wasn't replaced...any way, they didn't replace the pushrod if it's galled on the pump end. I've also seen twice engines assembled with breakin lube only on the lifter lobes, forgetting altogether the pump lobe.

[firefighter3931]

Thanks ff. My pushrod measures 3" only.i am using quaker state 15/40 diesel semi synthetic oil. Is that good enough oil to use???

Somehow you've lost .25 in of metal. You need to find out why and do an inspection on the bearings, oil pump etc...

Are you running a roller cam ?

Drain the oil and cut open the filter to see if you find any metal shavings.



Ron

[wrench]

pushrod is brand new mopar(put it in myself). like ff said ,will have to check the oil pump and filter. what beats me is the pump end of the pushrod is galled and the pump lever hardly shows any sign of wear(not even shiny) the pump lever is harder than the pushrod???

[firefighter3931]

The fuel pump rod may have been defective (inadequate heat treatment) or it could be an oil issue....either scenario is possible  


Ron

[68chgr]

The ame thing happened with my old Big Block a few years back.  I found the pushrod worn on one end only, I just don't remember which end but will assume the cam end.  I replaced it with a new rod, checked the oil filter for debris and flushed the oil pan. I did not find anything abnormal in the filter and just assumed this wore over a period of time due to incorrect hardness of the part.  It was a new (Mopar Performance) rod when the motor was rebuilt and I still have the original which is in next to new condition.  Just one of those things that you think you need to replace, but just not the case here.  Good Luck!!!

[wrench]

thanks for the info guys. i think the defective pushrod idea is the most likely.i will still have to check my pump and filter to satisfy myself though.just curious on how you flushed your oil pan?

[wrench]

removed the old pushrod from my old 383 and it looked heat treated,unlike the new mopar pushrod i had installed. soooo i put the hacksaw to the old pushrod and it the hacksaw couldn't touch it. tried that on the new mopar rod and it went through like butter.  Thanks ma mopar

[Nacho-RT74]

thanks god I got a NOS replacement around to change when times comes to that!!!!