94 6.5 NA problems...

[mohavewolfpup]

I help maintain a 94 Chevrolet/bluebird school bus with a NA 6.5 in it. Lately it's showing very low to no oil pressure. Did do several 100 mile trips without blowing up. What gives? Dash gauge shows low pressure, as does a mechanical gauge.

Anyone have any ideas? So weary of the lack of info out there, maybe she just needs to drive it into the ground?

 

[058hammer]

20lbs of tanerite might do the trick.

 

[mohavewolfpup]

It's needed for a dog rescue so I don't want it nuked, just cross eyed from the info out there. Very difficult to find a definitive answer

 

[towcat]

I help maintain a 94 Chevrolet/bluebird school bus with a NA 6.5 in it. Lately it's showing very low to no oil pressure. Did do several 100 mile trips without blowing up. What gives? Dash gauge shows low pressure, as does a mechanical gauge.

Anyone have any ideas? So weary of the lack of info out there, maybe she just needs to drive it into the ground?

what numbers does the mech gauge have?

 

[058hammer]

When was the last oil change? Does the oil smell like fuel? We need more info to really be of much help.

 

[mohavewolfpup]

Sorry for the late reply. Not sure on what the mechanical gauge said, believe it registered only 10 lbs or so. Will ask.

No fuel smell in the oil i've noticed.

Engine was put back together, still shows zero oil pressure.

The oil was recently changed (rotella 5w40 synthetic) since it sees service in 32 degrees and lower weather. That was it's 3rd oil change, before that it was 5w40 also (rotella)

Before that, at the recommendation of a guy with a powerstroke he said to use rotella 15w40. That worked well, until winter hit (and the super extended idling the driver does) thickened the oil up real bad. Using a heat gun, I managed to get it flowing again. Dumped two gallons of rotella 5w40 in it, and then drove it around the property. Drained, refilled, done. Pressure gauge still acted screwy after that.

Puzzling to me is that it has made several 100+ mile (one way) trips and it hasn't blown up.

Oil pump is fine per the mechanic. Doesn't appear to have spun bearings? At a loss at this point

 

[mohavewolfpup]

Someone recommended I just put two gallons of straight diesel in the crank case and idle for 5 minutes. Is this a hot idea? Sounds like a runaway waiting to happen...

 

[towcat]

Someone recommended I just put two gallons of straight diesel in the crank case and idle for 5 minutes. Is this a hot idea? Sounds like a runaway waiting to happen...

really bad idea.
if your bearings aren't ruined, pulling that stunt will do so.
i'd put 15/40 back into it and see what the pressure is. it should be warm enough by now.
also, where is the mech gauge being ported in at?

 

[mohavewolfpup]

really bad idea.
if your bearings aren't ruined, pulling that stunt will do so.
i'd put 15/40 back into it and see what the pressure is. it should be warm enough by now.
also, where is the mech gauge being ported in at?

I'll find out if they know where it was plugged in. Where should it be plugged in? Will a sun pro gauge/whatever I find at oreillys do?

I let a mechanic with more tools/supposed know how do it, but might be the time for me to get a crash course in this

 

[towcat]

I'll find out if they know where it was plugged in. Where should it be plugged in? Will a sun pro gauge/whatever I find at oreillys do?

I let a mechanic with more tools/supposed know how do it, but might be the time for me to get a crash course in this

for diagnostic purposes, any mech gauge will do. usually they are ported at the back of the block or the front of the block right at the top of the transmission web where the oil pump drive or vac pump depending on year. the most unreliable port location is the one in the valley of the block due to the proximity to the lifters. do expect to get a 10psi drop per foot on the block from the point where the oil pump is at to the port. so if you are ported at the front, it would be a 20 psi drop. these numbers are for GM oiling systems only.

 

[mohavewolfpup]

for diagnostic purposes, any mech gauge will do. usually they are ported at the back of the block or the front of the block right at the top of the transmission web where the oil pump drive or vac pump depending on year. the most unreliable port location is the one in the valley of the block due to the proximity to the lifters. do expect to get a 10psi drop per foot on the block from the point where the oil pump is at to the port. so if you are ported at the front, it would be a 20 psi drop. these numbers are for GM oiling systems only.

Would it be possible to tap into the factory location? Ditch the stock sender and plug in there? Or that's the unreliable point you are mentioning?

 

[towcat]

Would it be possible to tap into the factory location? Ditch the stock sender and plug in there? Or that's the unreliable point you are mentioning?

where is the stock sender at on your motor?

 

[mohavewolfpup]

where is the stock sender at on your motor?

Far left of the engine, tucked in a corner below HVAC lines. I'm not sure if I have a photo of it. Bus is 90 miles from me, so going on memory. Positive it is on the left of the block

 

[towcat]

Far left of the engine, tucked in a corner below HVAC lines. I'm not sure if I have a photo of it. Bus is 90 miles from me, so going on memory. Positive it is on the left of the block

you positive there's nothing on the rear of the block? if it's on the front, you have your work cut-out for you since it's a van.

 

[mohavewolfpup]

you positive there's nothing on the rear of the block? if it's on the front, you have your work cut-out for you since it's a van.

That is on the rear of the engine. It's a p30 chassis. I remove the hood from the inside, ********* cover that snaps on in 4 places.

Sender is slightly angled on the left side of the block, rear. Have a bad photo of it, but the android tablet refuses to work and download/attach it