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OT, Chevy Oil Pump

I

IndianaRed

Member
What are the common symptoms of an oil pump going bad? Mine is taking longer and longer to get the pressure up. Low when cold, normal when warm, but takes 10 or 15 minutes of driving to get there, after letting it warm up a few minutes before driving. 4.8 V8, 486,000 miles. If bearings were worn I'd have low pressure when warm wouldn't I?
 
My Guess is the sump or Pick up tube it getting
plugged, as the oil warms or thin's alittle
pass's threw the sqreen easier. But with 468K
the bearings can't be like new either. Remove
pan & clean Sump or install New one, check the
bearings while your there. If ya don't do
something soon you will have bigger problems..
A Oil pump can't produce pressure without Oil..
 
I'd ck the gauge and the second thing would be the screen on the oil pump. the fiber off the timing cover gears like to clog up the oil pump screen. the gauge is so ez to check that i'd start there.
 
Make no mistake, at half a million miles, you're thru the babbit. Engine is gently trying to tell you that it requires attention.

However, and a "just for what it's worth", a VERY COMMON ailment on the GMs is the electrical sender.

Allan
 

If that has a timing chain, it should have been replaced (and the gears) every 100,000 mi..
That would be my 1st concern...
The oil pump must be working fairly well, if you have normal pressure with the recommended oil..
About has to be either the oil pressure sending unit or possibly the pick-up screen..
Has a valve cover been off lately..?
I have seen crud as high as the valve spring retainers in 100,000 mi with Quaker State and I changed the oil and filter every 2,000 Mi in my brother's '68 Camaro V-8...
Surprisingly, the Bearings were as good as new...but the Varnish had built up to the point that it took a 20 Oz hammer to drive the lifters out..!!
If it has that kind of build-up in it, I would drop the oil pan and FLUSH it out with the oil pan and valve covers OFF, then run a Quart of Rislone with the regular oil the next oil change or two..
I would not worry about the bearings..until it really does need a re-build..

Ron..
 
some time ago onan 87 ford 460 timing gear (fiber or plastic) went bad. Replaced with steel. Driving at 55 oil pressure ok, at 70 on interstate drop to 10 lb. Changed oil added 1 qt of RISOLONE ordered from napa , keep speed down. drove one round trip 200 miles, changed filter added only risoline. another round trip changed oil and filter added another qt. another trip changed filter , Next trip opened it up, no perssure drop even up to 85 mph. Each time opened old filters and found old timing gear material and sludge. Sever years later carries 60 lb on guage at all speeds.
 
Engine doesn't owe you anything. New GM crate engines are surprisingly value priced. Good warrenty too.
Time will tell if the 2007 and later diesels will last as long as your gasser. With a minumum of repairs and cost per mile.
 
Nope, doesn't owe me anything, but I'd sure like to drive it for a while after it's paid for, and that's November. Do you think I'm upside down?
 
You know, that's what I've been hoping it might be. Other than this issue, she doesn't smoke, miss, nothing. Starts and runs like new, as far as I can tell. I know other drivers that are over 700,000 on there's, without ever having the engines opened. Not even for those pesky manifold gaskets.

Is there a way I can test the sending unit?
 
You know, that's what I've been hoping it might be. Other than this issue, she doesn't smoke, miss, nothing. Starts and runs like new, as far as I can tell. I know other drivers that are over 700,000 on there's, without ever having the engines opened. Not even for those pesky manifold gaskets.

Is there a way I can test the sending unit?
 
I had 100,000 miles on it in six months, no way I was going to change the timing chain that soon, couldn't afford to if I wanted to.

This motor has never been opened up, and I'm not going to until I absolutely have to.

Mileage and performance are same as new. No smoke, no misses, no nothing.
 
I'd stick a mechanical gauge on it and check the pressure first. It could be the sender... Otherwise the symptoms suggest to me that it's likely a problem on the suction side of the pump. Either obstructed or leaking. As you say, if the bearings were really bad I would expect poor pressure at idle when it's warm.
Beyond that... if you find that the bearings are bad when you open the pan up... I'd suggest going with a crate engine. You can doctor the bearings today and next week it'll be a head... then the rings... then a lifter.
You obviously use it every day, a lot... so i can't imagine you want the downtime never mind the expense of various repairs. Drop a crate in it when the time comes and fix the problem.

Rod
 
how in the heck were you putting, on average, 555 miles a day , 7 days a week for 6 months? (100,000 miles divided by 180 days ( 6 months) ) Bill M.
 
I know, sounds crazy and unlikely, but that's how much I was driving then. This is the first new vehicle I ever bought, new in 2006, November. The first year I put 178k on her. I was basically a miniature trucker, long-hauling almost non-stop. Many, many 1,000 mile days. 20 trips to California. It's amazing how well this unit has held up. It's a 3/4 ton van, not set up for towing at all, spent many a day in 2nd gear, heading west into strong winds, pulling a too heavy trailer over the Rockies and Sierras just trying to hold 50mph in the 120 degree dessert. It was unreal, and I don't recommend it. That little 4.8 was screaming and getting 6mpg! It was brutal.

All I know is that there is NOTHING coming out of Asia like my Chevy van!

Repairs thus far:

1 - Alt. (415k) About $150
1 - Water Pump (430k) About $150
2 - Wheel Hubs (first at 365k) About $150 each
1 - Serp Belt (390k) $30
1 - AC Belt (455k, wasn't that bad) $20

Still on 2nd set of plugs, original wires.
Never have changed tranny fluid. (Dex 5 or 6)
Everything else is still factory. Drive train never touched, other than replacing the rear u-joint twice now. On second set of shocks, but due again. Original muffler, cat convertors, fuel pump, everything.

And check this out. I had the original factory brakes on it for over 300k. Took them off I don't know how many times to replace them and they never showed any wear. The rotors a little, but not the pads. Amazing. I finally changed them just because I couldn't stand it anymore, but they weren't bad.

People call it snake oil, but I've kept Lucas in the oil, fuel, tranny, and rear end, and I have to think it's made a difference. Plus I don't wait for the change oil light, which usually comes on around 15k. I still change at 3-4k miles. Conventional oil with Lucas is just as good as Mobil-1 if you ask me. And changing more often is better than leaving even synthetic in for 15k, even with a filter change.

The one problem it did have is the ever too common chevy intake manifold gasket started leaking at just over 150k. But instead of replacing someone told me to try those six packs of little brown tablets for sealing radiators. Put them in, leak stopped and hasn't come back. Changed from that crappy pink radiator fluid to green.

A lot of people say, "Oh, well that's all highway miles". Not true. Yes, in the beginning, but at about 230k I had to quit when fuel prices went so high. Went back to being a local delivery driver. I think hours are even now between highway and city. Or at least very close. And even those early highway miles were brutal, overloaded, hot, asking way too much out of her.

This truck is bulletproof, and magic.
 
Ron,

I'd like to drop a new motor in, well not really, I want to see just how far this one really wants to go. But anyway, can't afford one. I'm still trying to pay this thing off!! 6 more payments, do you think I'm upside down?

How/where do I put the mechanical guage on it?

Here's the part I left out of the original post. Don't laugh too hard.

Winter of '08 got really cold her in Feb, like almost 20 below at night for a couple weeks. Was scaring me starting her up in the morning. Went to get a block heater, magnetic type. Found everything is aluminum, the block, the pan, and the tranny. So, smart guy that I am, I put a hot plate under the pan. Well, I apparently put it too close to the pan and too hot. Boiled the oil out of it, but didn't know it until about the 5th day. Driving late at night, oil guage started bouncing and going down. Thought it was all over. Pulled over, checked oil, nothing on the stick but nasty thick goo on the very tip. Unbelievable! Well, I was 200 miles from home, and as always, not enough money. So I filled it up with oil and went home. Guage bounced for 20 minutes or so then started coming up and got back to pretty much normal. But I know I hurt her. Crud and crap all in the oil passages. That makes this story even more unbelieavble, that she came back from that. Did all I could to flush it out with Seafaom and other stuff, after about 3 oil changes it started looking normal when draining oil. But that makes me think I occasionally get a chunk that breaks lose and clogs a passage or the screen.

I would've pulled the pan already but you have to lift the motor to get the pan off, and since it hasn't run poorly or smoked or use any oil, (at all), I've just kept rollin, and hoping. This low pressure started over last winter, little my little. Now even in the summer I have to warm her up. So it's probably clogged screen or something, but maybe not. There's no sludge in the bottom of the pan. I can put a long thin screwdriver into the drain hole and slide it around and nothing comes out, (like it did for the first few oil changed after the boil-down incident). And I can even get the screwdriver up on the pump screen and run across it and I feel all the little ripples of the screen, not like it's all crudded up, but that's not a certainty. I think the Lucas may have been what saved saved me.

The fact that she doesn't smoke, hasn't lost any mileage, and doesn't seem to me to have lost any power from when new, gives me hope that maybe it is just the sending unit.But then again, that boil down may be coming back to haunt me.

Appreciate your input. I know we've disagreed on some OT stuff before, thanks for helping me with this.

Brian
 
Someone told maybe the diaphram could be going out in the pump? I'll admit, I don't really know pumps. I rebuilt my H motor myself, just barely, but I don't know much. Any help is appreciated. Made a few more posts on this with more info, if you have time you might check them out, might even be amused.

Thanks for the input.
 
Alan,

I know you know a lot and I respect your knowledge and experience. So what's "thru the babbit" mean? I know it's a pain explaining to dumbheads like me, but I've heard you say that before, and when you did in was in a context that made me know what it meant, but now I can't remember.

And although you sure may be right, I know quite a few other guys with these same motors that are over 700k without ever opening them up. It's really amazing to me.

You know, I bellyache as much as the next guy about the price of new vehicles. But if you back out the inflation and compare a car/truck of today with those of the 60's thru 80's or even 90's, there's no comparision. We're getting A LOT more for our money today. Change the oil and keep up minor maintenance and they last forever.

Makes me wonder why anyone would buy a darned Toyota or Nissan truck. Chaps my backside really, especially when I see farmers out in the country with them. I just don't get it.
 
(quoted from post at 19:19:56 06/17/11) I know, sounds crazy and unlikely, but that's how much I was driving then. This is the first new vehicle I ever bought, new in 2006, November. The first year I put 178k on her. I was basically a miniature trucker, long-hauling almost non-stop. Many, many 1,000 mile days. 20 trips to California. It's amazing how well this unit has held up. It's a 3/4 ton van, not set up for towing at all, spent many a day in 2nd gear, heading west into strong winds, pulling a too heavy trailer over the Rockies and Sierras just trying to hold 50mph in the 120 degree dessert. It was unreal, and I don't recommend it. That little 4.8 was screaming and getting 6mpg! It was brutal.

All I know is that there is NOTHING coming out of Asia like my Chevy van!

Repairs thus far:

1 - Alt. (415k) About $150
1 - Water Pump (430k) About $150
2 - Wheel Hubs (first at 365k) About $150 each
1 - Serp Belt (390k) $30
1 - AC Belt (455k, wasn't that bad) $20

Still on 2nd set of plugs, original wires.
Never have changed tranny fluid. (Dex 5 or 6)
Everything else is still factory. Drive train never touched, other than replacing the rear u-joint twice now. On second set of shocks, but due again. Original muffler, cat convertors, fuel pump, everything.

And check this out. I had the original factory brakes on it for over 300k. Took them off I don't know how many times to replace them and they never showed any wear. The rotors a little, but not the pads. Amazing. I finally changed them just because I couldn't stand it anymore, but they weren't bad.

People call it snake oil, but I've kept Lucas in the oil, fuel, tranny, and rear end, and I have to think it's made a difference. Plus I don't wait for the change oil light, which usually comes on around 15k. I still change at 3-4k miles. Conventional oil with Lucas is just as good as Mobil-1 if you ask me. And changing more often is better than leaving even synthetic in for 15k, even with a filter change.

The one problem it did have is the ever too common chevy intake manifold gasket started leaking at just over 150k. But instead of replacing someone told me to try those six packs of little brown tablets for sealing radiators. Put them in, leak stopped and hasn't come back. Changed from that crappy pink radiator fluid to green.

A lot of people say, "Oh, well that's all highway miles". Not true. Yes, in the beginning, but at about 230k I had to quit when fuel prices went so high. Went back to being a local delivery driver. I think hours are even now between highway and city. Or at least very close. And even those early highway miles were brutal, overloaded, hot, asking way too much out of her.

This truck is bulletproof, and magic.
Click to expand...

Deep and smells bad.
 
I'm not sure where the sender will be on that engine but I'd expect it on the lower part of the block, probably handy the oil filter. Just look for a wire. take the sender out and install the gauge. If you want to check both, install a 'T' and put both the sender and the gauge on. That said... I think you found the problem with the coked oil. Likely a chunk of that is stuck in the pickup and it's restricting flow. When the oil thins out it's able to flow sufficiently (somewhat) through the obstruction. To that end, the Lucas is not helping you because it's a high vis additive... Higher viscosity, less flow. Less pressure. If the problem was worn bearings then the high viscosity would help.

I know how you feel about not wanting to spend the money on a crate engine. Believe me, I do. used to be the same way... We put four Windsor's in an F350 we had. The last one was a NAPA reman. The other 3 were half as$ed rebuilds. If I had to do it over again the first one would be a reman or crate engine. It would go on plastic until I could pay it off. Just saying...

At this point though... you need to at least drop the pan and clean the sludge out.

Rod
 
Really, Slick? Some reason I would make it up? Go troll somewhere else. I guess you're just another loser with nothing better to do than run around making smart azz remarks.

Go watch some more TV, drink another beer, and get a little fatter.
 
I'm telling ya, I don't think there's any sludge in the pan anymore. That boil down was 2 1/2 years and over 200k miles ago. But I do think it's likely that there are some restrictions somewhere. I'm thinking out at the farthest points from the pump.

For about 3 oil changes after the cooking, I was getting sludge when draining, and I would slide a screwdriver up in the pan and pull out more. But since then nothing. I think it's probably in the pick-up or out in a passage. Last oil change I added a full bottle of Seafoam and ran it 3000 miles. A couple of times when starting I got some puffs of bluish white smoke. I think that was some chunks coming loose and blowing through?

And I just meant that the Lucas probably saved me right then, when the oil was gone, left a little sheen in the cylinders for lube. I don't know.

And that Lucas raises my oil pressure. I went without for the last 3 or 4 oil changes, about 6 weeks, and my pressure was noticably lower. Put it back in last week, and back up it went, by 3-5 pounds.

I've got a Haines manual, I'll see if it shows me where to hook up a mech guage.

Thanks again.
 
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