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Login to post Forums » Grassroots Motorsports » Need insight: 1994 Suburban 1500 engine

May 26, 2010 9:03 a.m. slefain Dork

My good friend was driving his Suburban and it make a loud "bang" sound, the oil pressure tanked and it shut off and would not start again. We both assume it broke the oil pump driveshaft, but we don't know if it shut down as an automatic engine protection system. Anyone know if such a a thing exists in GM trucks of that vintage?

The other question is for the worst case scenario. He was told that '94-96 GM trucks used a special engine block setup due to some mounting brackets. I call B.S. That 5.7L engine should be the same from 1988-1998 and be available at K-Mart.

He need to get the 'Burb back up and running to move his family around (4 kids). He's a Ford guy so I'm trying to help him out on the dark side of things.
May 26, 2010 9:14 a.m. Grtechguy SuperDork

hmmm....what rod snapped....that is the question. use car-part.com to find the interchange
May 26, 2010 9:57 a.m. iceracer Dork

I don't think the pump shaft would make a "loud bang". Something more serious broke.
May 26, 2010 10:48 a.m. itsarebuild Reader

maybe the distributer drive gear broke free from from the cam? that would shut down the oil pump and the distributor. didnt that happen to the V8 orange rx7 at the challenge last year? i've never heard anything about the mounts being different but i dont have a 1994 suberban either.
May 26, 2010 10:51 a.m. slefain Dork

He was just sitting at idle in traffic on I-75, so I have a hard time thinking it lunched a connecting rod.
May 26, 2010 11:07 a.m. Wonkothesane Reader

It seems like C-Rods always choose the least-stressful time to snap... Of course, they were pushed to the point of breaking earlier, but some how just hold onto life until you're about to pull out of a parking lot or idling somewhere. :)
May 26, 2010 11:21 a.m. John Brown SuperDork

slefain wrote:

My good friend was driving his Suburban and it make a loud "bang" sound, the oil pressure tanked and it shut off and would not start again. We both assume it broke the oil pump driveshaft, but we don't know if it shut down as an automatic engine protection system. Anyone know if such a a thing exists in GM trucks of that vintage?

The other question is for the worst case scenario. He was told that '94-96 GM trucks used a special engine block setup due to some mounting brackets. I call B.S. That 5.7L engine should be the same from 1988-1998 and be available at K-Mart.

He need to get the 'Burb back up and running to move his family around (4 kids). He's a Ford guy so I'm trying to help him out on the dark side of things.

There were very many variations of that engine between 1988 and 1998 but 1988 - 1995 should be interchangeable. 1996-1998 used a different head and timing cover among other differences.
May 26, 2010 11:45 a.m. carzan Reader

If the timing chain let go, a valve hitting a piston or the remainder of the chain getting thrown might make a bang and the engine would shut down. ??
May 26, 2010 11:49 a.m. Pat Reader

Did it shut off immediately at the "bang"? When exactly did the oil pressure tank?

What I'm getting at is if it went bang and shut off immediately, oil pressure would surely drop to zero when the engine stopped. If it had no oil pressure, it was still running and eventually it went bang and shut off, then it could be a very different story.
May 26, 2010 1:23 p.m. slefain Dork

My friend sent me a better description of the problem:

"The engine starting ticking about five minutes before it ceased. I was stuck in rush hour traffic on a divided highway and knew I needed to get off the road and check it, but by the time traffic moved enough that I could get off the tick became a serious knock. It died at the intersection with a loud thud and three quarts of oil dumped on the ground. From the looks of it a great deal of oil was coming out the front crank seal. I’ll know more when I pull the block in a week."

So, anyone got a motor collecting dust?
May 26, 2010 1:50 p.m. DILYSI Dave SuperDork

Yeah - that ain't no small problem.

Sounds like a trip to Kmart, or Pullapart in this case, is in order.
May 26, 2010 2:18 p.m. carzan Reader

Ouch!
May 26, 2010 2:56 p.m. novaderrik Reader

look at is as an opportunity to upgrade to a 96-99 vortec motor- get a running engine out of a wrecked truck, install a GM vortec TBI intake manifold (912496821 new at your favorite GM dealer, Summit, Jegs, etc or get a used one from ebay), and bolt it right in place of the stocker with all the 94 accessories. this way, you get the good vortec heads, higher static compression, and a roller cam. it's an easy 50hp gain that will bolt right in once you swap the proper intake manifold on and drill the water bypass with a 3/8 drill bit to allow the use of the '94 water pump.

edit: holy crap.. i just looked up the price of that vortec TBI intake- it used to be about $200 and has doubled in price..
May 26, 2010 3:07 p.m. Buzz Killington Reader

still cheaper than a new truck.
May 26, 2010 6:34 p.m. plance1 HalfDork

could a rod have let go and the hole hasn't been found yet, making you think the oil is coming from the front seal?
May 26, 2010 6:47 p.m. CaptainSpaulding New Reader

Thats what I am thinking. Big hole in the pan and the oil BP'ed its way out.
May 27, 2010 6:54 a.m. 914Driver SuperDork

Tick, tick, tick = no oil to the lifters?

No oil to the journals, crank etc.

Bang = rod seizing on the crank, letting go and exiting through the pan.

Regardless of how it started, a reman or an engine with known history would be easier than rebuilding this one. Find the best motor you can afford and swap it in. It's just nuts & bolts. Two guys can get it done in a weekend.

Dan

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