OT/problem with truck

Help..........I have a problem with my truck.

It's a 1996 GMC Seirra 2500.

It was in the shop about 1200 miles ago for some repairs, most of which were unrelated to the current problem; brakes, ball joints, ect. It also got a tune-up, some fouled plugs were replaced, and the oil was changed; which may be related to the current problem.

Yesterday, on the way to town, I noticed a clicking sound. On the way home it went away and everything seemed fine. No idiot lights, no abnormal gauge readings, no more noises.

Today, on a trip to my in-laws, the noise started up again. As the trip went on I noticed the oil pressure gauge bouncing up and down. By the time I got home it was dropping to zero but not staying there. The truck sat for awhile. When I started it again; that's right, I started it again without checking the oil....you can guess where this is going......the gauge read 0 for several seconds then popped back up to normal.

If the pressure gauge was up (40 or so) little or noise could be heard. The farther down the guage went the louder/more intense the noise gets.

At that point I finally decided it wise to check the oil so I pulled the dipstick............ NOTHING!

Okay, I know it was stupid to ignore the noise in the first place and I should have checked it out yesterday; but I didn't............

There are no obvious leaks. The valve coverers are clean, no oil drips underneath, or other obvious signs of oil loss. Of course I'm obviously not an expert. The one thing I did find is moisture inside the tail pipe. I rubbed my finger in there and.........black!

Is this a head gasket? If not what? Could this be connected to the work done on the truck last week? Any other thoughts, ideas, advice, suggestions or comments: other than I should not have driven it after hearing the noise.

Thanks,
Drk

Fill up the oil. It is not hurt yet. Now keep an eye on the oil level like a hawk. I'll bet it uses more oil than it did. Park it over a clean cardboard to find leaks. JimN

Don't know if this is the case here or not but will tell you what happened one time when mine acted like that. Was going down the road in a 93 K1500 with a 5.7 and notice a ticking sound. Looked down all gauges were fine. Went a few miles later and it got louder and oil pressure was bounce'n down to 0 then right back up. Pulled over and checked the oil, nothing on the stick. Went and got a quart out of the back and started to put it it in. The valve cover was full of oil, I mean it ran out when I took the cap off. Sat there a while and it slowly went down, the ports where the oil runs back down out of the valve covers was pluged almost all the way up. Drove slow to town, picked up a bottle of sea foam, drove home, stoped 2 miles before I got home and put the sea foam in the oil, went the rest of the way home and changed oil while it was still hot. 50,000 miles later it has never happened again.

Good luck.

Dave

They may not have put enough oil in it and thats why you had no oil. The 350 in my grandpas old truck will show no oil on the stick but there will be enough there for the pump to get. My guess is there was enough oil not to trash the engine.

Like was said, fill it up and watch it.

Check everything!! I once had a problem simialr to this. I noticed a clicking noise, checked the dipstick. Nothing, added 4 qts, still nothing, crauled under, The dipstick tube had rusted through, and the dip stick was hanging down and not even going into the oil pan, drove home 4 qts over, Upon inspection, the clicking noise was a broken radiator mount, alowing the radiator to move back just enough for the fan to tick the shroud. good luck getting a handle on this.

Don't know about GM, but my Fords require 7 quarts when the oil is changed. None of the places I have found know that. I have taken to checking it before I leave the shop and making them fill it up. They always claim it will be overfull until I pull out the owners manual and show them the capacity chart.
Ding Bats!

thanks so much everyone. I will check the valve cover side and see what's there. If there is oil there I'll try sea foam and an oil change. What is sea foam anyway?

If that's not it I'll just fill it and watch close to see what happens.

Oil is the life blood of the engine----No oil---No engine. It's just part of maintenance. Check the oil before you start the engine first thing in the morning. The ONLY engine I ever saw survive a no oil lock up was an IH 345 in a scout. Put diesel fuel in it and drug it around the field with a tractor until it broke loose. Ran for another year & was traded off.

In an engine that old, you could have a sludged up oil pan and pickup screen. This forces the oil pump to scavenge for oil and sometimes it cannot get enough. I had this happen in an S-10 with the 2.8L engine. Finally solved the problem with several treatments with Rislone, diesel fuel soaks (engine NOT running) and scraping around the inside bottom of the oil pan with a hanger wire to break up the sludge. The quicker solution though is to pull the pan and clean things out. (If you like pulling the engine).
Make sure you have not at some point bottomed out and bashed the oil pan in against the oil pick up screen also.

okay, I checked things over again this morning. Still no drips or leakes that I can find. Very little on the dip stick, but some. Nothing on the other side either.

That means the oil is going somewhere. Where?

I'll go ahead and put in some quality oil and watch it like a hawk.

Fouled plugs and high oil consumption on a '96 is a sure sign the plastic lower intake gaskets have failed.They drop down a bit in the middle and away from the sealing surface.

Thanks,

What are plastic lower intake gaskets? Is that what is called a pvc valve? Someone mentioned that.

from what i saw on goss's garage,it may be burning oil and the catalytic converter is burning up any evidence-black smoke.

Sea Foam is a snake oil stuff that I think works pretty good. I always forget to put sta-bil or what ever it's call in lawn mowers and ever thing else that only gets used half a year. Drible a little in the carb and they always start right up. If you put some in the oil of about any thing that has been setting a while or you just think is kinda cruded up and run it till it gets hot and then change the oil it shines everything up inside pretty good, or at least from what I have seen.

Yes I know alot of folks on here don't waste money on snake oils but I have always had good luck with it.

Good luck.

Dave
sea foam

Kyplowboy has your answer.The oil return holes are plugged in the cylinder heads.The engine is gummed with oil deposits.If you remove the valve covers you will see the problem.It will look like black mud under the covers.Dig all you can out with a screwdriver and a narrow putty knife.Reinstall the covers and go get a couple of quarts of Rislone from your Auto Parts store.Go ahead and pour 1 qt. in the engine now.Start it and let it warm up and then drive it a few miles while watching your oil guage.It should show good pressure now.The Rislone is cutting the deposits loose now as the engine runs.Drive it only a few miles then drain all the oil and Rislone out of the crankcase.You will be astounded at what you will see in the drainpan.Go ahead and change the oil and filter.Drive it about 500 miles and repeat this using the other qt. of Rislone.When you get it cleaned out start changing your oil every 3000 miles.The reason you don't see oil on the dipstick is because the engine is gummed up the oil is trapped in the upper part of the engine.It has no quick path back to the oil pan.If you check it with the engine cold "after it sits for several hours" it will probaly check full.The noise you hear is the hydraulic lifters rattling due to lack of oil and pressure.Run it like this for long and you will need an engine.This truck probaly calls for 5w30 motor oil.I would use a good 10w30 wt. in it now and keep it changed at 3000 mile intervals.Good Luck.

They are intake gaskets which are made of plastic.Called lower because there is an upper plenum gasket and a set of lowers on the Vortec.

A better lower gasket is available.Made from steel and rubber and made by fel-pro called Perma-dry.

You better fill the engine w/oil and make sure it's worth fixing before sticking money into it.
A lower intake job runs about $550.

Wow, thank you all for the advice. It is all very helpful. I've learned a lot.

I filled it up (four quarts), started and let idle till warm, all the time watching the pressure gauge. It jumped right up to around 60. It has stayed there all day. I drove about 100 miles total and the gauge never moved.

We replaced a pcv valve (not sure what that is) to start with and will go from there.

I did make a long run, 600 miles, pulling a heavy stock trailer a week ago. The mechanic thinks that may have just been to much. I'll keep a close eye on things and hope for the best.

If it holds decent pressure and does not loose oil fast I'll try cleaning out the valves and pan.

Thanks again............I'll let you know how it turns out.

Isn't it possible the truck was given back to you without oil? Maybe I didn't pay attention. This can and has happened before. Once to me in 1962. Also oil smoke is blue unless I am color blind(possible.) Dave

That is possible but since I didn't check it right away I have no way of knowing.

Since the truck has needed very small amounts of oil added between changes in the past and the long distance I pulled a heavy trailer, I'll go with whay the mechanic thinks for now.

I'll just keep an eye on it.

GM engines are bad for the oil drain holes getting stopped up. My grandmother had a Pontiac station wagon with a 307 that smoked like a freight train due to this. A quick cleaning of the drain holes and it was fine. Your motor is still probably ok even though it was starved for oil. I was driving an old Ford pickup with a 352 that leaked more oil than I thought down I-40 from Raleigh, NC to Wilmington one time and just as the interstate ended it started missing and knocking. I pulled off, put 2 qts of oil in it, and drove it for several more years. It got so low the lifters were no longer pumped up.

Here is an update on my GMC.

After filling the oil and watching things closely for two days I took it back the mechanic and explained what happened. We decided to change out the PCV valve.

This week I have driven around 400 miles, 200 of which was pulling my tairler with four cows on board, and it has not burned an ounce of oil. That's good!

I've babied it a lot. I've been carful not to push it and kept the RPMs under 2000.

It was suggested that pushing it, on long trips, pulling a heavy trailer, combined with a bad PCV valve caused the oil to burn off in the catolatic converter. Maybe?

I'll just keep watching and taking it easy on the old truck.

Here's hoping the problem is solved.