Rebuilt motor brought truck in for exhaust work died on the way home...

[TJ79Cheyenne]

Hey guys,
I recently rebuilt the 5.7 TBI motor for my 87 Silverado. Had everything put back together and fired her up (with help of a friend with more experience). It was running fine so I brought her up to around 2000 RPMs and it started loping.. Well I decided to let it go until it gets warmer out so I brought it to an exhaust shop to put the finishing touches on her. I was almost back to the house and she just died. Look on the ground and it's dripping oil from somewhere(still haven't figured it out yet). Put a couple quarts of oil in her and tried to fire her up to no avail.. Had my buddy hook his jumpers up and it eventually fired up. Would the timing being off slightly prevent the motor from starting while warm? Also there wasn't any oil in the inspection cover so I'm hoping it's not the rear main...

Thanks,
TJ

 

[HotRodPC]

You've got alot more splaining to do about this matter. Dies like lost power, lost spark, sputter out of gas? How low did the oil get? Low enough to drop the oil pressure? The Fuel Pump relay on a TBI system get's a signal from an oil switch. If you lose oil pressure, the fuel pump relay will shut the fuel pump off. And guess why??? Cuz of these situations right here. Do you realize that switch just saved your ass and your new motor. And yes this does make sense. Cuz the relay will not come back on, UNTIL the switch detects good oil pressure again. So you prolly had to crank it for awhile to get the override oil switch to give the OK. You owe a GM engineer a biggo fat wet kiss.


So now, find that oil leak and get it fixed.

 

[TJ79Cheyenne]

Yeah it dropped the oil pressure to 0! There was nothin' on the dipstick when I checked it so that got me worried. That would make sense that the relay would shut the fuel pump off, someone explained that to me before just slipped my mind.

 

[chubble]

You've got alot more splaining to do about this matter. Dies like lost power, lost spark, sputter out of gas? How low did the oil get? Low enough to drop the oil pressure? The Fuel Pump relay on a TBI system get's a signal from an oil switch. If you lose oil pressure, the fuel pump relay will shut the fuel pump off. And guess why??? Cuz of these situations right here. Do you realize that switch just saved your ass and your new motor. And yes this does make sense. Cuz the relay will not come back on, UNTIL the switch detects good oil pressure again. So you prolly had to crank it for awhile to get the override oil switch to give the OK. You owe a GM engineer a biggo fat wet kiss.


So now, find that oil leak and get it fixed.

HR This is a VERY useful piece of knowledge to know about!

 

[HotRodPC]

Yep, That's the whole purpose of that little oil switch. Worth 10x it's weight in gold. And it paid off for you this time bigtime. Shoulda bought a lottery ticket on your way home that day. You're lucky day.

 

[TJ79Cheyenne]

So what do ya think about this problem? (Have an idea just getting other peoples perspectives) I bought a new battery for the truck and it wont crank over on its own. Needs the assistance of a battery jumper on start mode. I think its from the distributor being off a bit...

 

[HotRodPC]

Is this all the time, or just when the motor is warm or hot? Vapor Lock is why I ask. Or is it all the time? If it's all the time, chances are the starter is old and wearing out. It may have worked fine on the old motor, but now you have a new tighter motor with higher compression and the tired starter is stuggling to crank it over. The added juice from a jump box is putting a band aid increasing the amperage so the starter will operate. A dose of Geritol if you will.

 

[shortboxchevy77]

You've got alot more splaining to do about this matter. Dies like lost power, lost spark, sputter out of gas? How low did the oil get? Low enough to drop the oil pressure? The Fuel Pump relay on a TBI system get's a signal from an oil switch. If you lose oil pressure, the fuel pump relay will shut the fuel pump off. And guess why??? Cuz of these situations right here. Do you realize that switch just saved your ass and your new motor. And yes this does make sense. Cuz the relay will not come back on, UNTIL the switch detects good oil pressure again. So you prolly had to crank it for awhile to get the override oil switch to give the OK. You owe a GM engineer a biggo fat wet kiss.


So now, find that oil leak and get it fixed.

Unfortunately that oil pressure switch killing the fuel pump wasn't really designed to save the engine due to low oil, it was actually designed to stop the fuel pump from continuously running in the event of an accident. I've seen many TBI 350's seized due to the breaking of oil cooler lines or simply running out of oil. Usually by the time that system detects no oil pressure and kills the pump its often too late and the damage is done on the bottom end. I'm going to guess and say that you partially seized the engine, especially if it turns over hard cold.

 

[HotRodPC]

There's some truth in that. Let's hope not the case this time though.

 

[TJ79Cheyenne]

It was usually when it was warm. Hard to say now since its been so damn cold these last couple days.. :/ hopefully it didnt seize on me. Hate to find out that all that work went to **** and that i have to find a new motor

 

[offroad-cowboy]

Consider your self lucky something knocked a hole in my oil pan causing it to run with out oil and locked up christmas eve 325 hp full roller tbi 350 down the drain thanks to my mother not watching my gauges when she had the truck

sent by telegraph from my k30

 

[MrMarty51]

 

[HotRodPC]

It was usually when it was warm. Hard to say now since its been so damn cold these last couple days.. :/ hopefully it didnt seize on me. Hate to find out that all that work went to **** and that i have to find a new motor

So it doesn't have a problem turning over like normal when it's the first start of the day or in cold weather? If you timing maybe advanced to far?

 

[TJ79Cheyenne]

Turns out the rotor in the distributor caught the cap and tore up the distributor. So I sunk a new dizzy in (on warranty of course) I'm waitin for it to warm up before I try to do any more work on her...

 

[HotRodPC]

Turns out the rotor in the distributor caught the cap and tore up the distributor. So I sunk a new dizzy in (on warranty of course) I'm waitin for it to warm up before I try to do any more work on her...

For that to happen I think the dizzy shaft would have had to of been bent. Replacing the dizzy was probably a real good idea.