2001 Tahoe 4.8l oil issue

[Fless]

A compression test doesn't always show a head or head gasket problem but should be done. You can also pick up a kit that will check for exhaust gas in the coolant.

 

[01BlueTahoeGuy]

I will have to talk with my father in law to see what he meant about it using coolant. I do know he has never over heated it.

From what I have gleaned from researching it, these are notorious for ghost leaks..........

I am hoping that I can get some more miles out of it before major surgery.

I also question the diagnosis of the shop saying he needed a new engine.

 

[OR VietVet]

I will have to talk with my father in law to see what he meant about it using coolant. I do know he has never over heated it.

From what I have gleaned from researching it, these are notorious for ghost leaks..........

I am hoping that I can get some more miles out of it before major surgery.

I also question the diagnosis of the shop saying he needed a new engine.

When you read thru threads here and see how many times shops have told members here or their relatives that they need a new engine and actually need a new engine less than 10% of the time, it really bothers me what the repair industry is doing, IN SOME SHOPS. A shop trying to rip off my mom is what got me in the industry for 35+ years. We recommend so many inspections and tests here before doing anything like that. Like @Fless said, a compression test does not always show problems because sometimes the temp of the engine and swelling/contraction of metals involved all have to line up at the right time to show a problem. The exhaust gasses test is a great one too. At my shops we used the exhaust gas chemical test but we also would use a 4 gas analyzer and remove the radiator cap and with engine running, from cold and warm up to hot, we could hold the exhaust pipe probe close to radiator neck and sniff for exhaust gasses. This test was very accurate. Especially when you consider that the probe was in the open air above the radiator neck and if it smelled exhaust gasses, it had to be pretty strong sign of a problem. You had to be careful not to get the probe in to the coolant so you held that probe tip about 1" above the exposed coolant.

I would guess, no guarantees, that your engine is not *****.

 

[MassHoe04]

I would expect the gauge to read near the middle of the dial (about 210 +/- a couple degrees either side) after maybe 5 minutes tops, unless it is super cold. Then 210 by maybe 10 minutes...

The fact that you are reading 180 after 15 doesn't seem right to me. Maybe just a bad temperature sensor sending incorrect information.

Go ahead and do your pressure testing. No harm in that. Check the levels and looks of the oil, coolant and transmission fluid. If levels hold steady and all look good (not milky, dirty, etc.), I would just change the oil again after maybe 100 miles or so and keep an eye on things. If everything remains unchanged and the oil looks good at that 100 mile change, I don't think I would lose sleep.

If it looks OK (no visible leaks or fluid loss, no fluid cross-contamination), smells OK (no odors up front or at the tail pipe, no sweet smell, no blue smoke or white plumes), sounds OK (no major clanks, bangs, ticks or knocks)...
You might just be OK.

Positive thoughts and fingers crossed!

Mechanics seem to not repair much of anything anymore. Now they want to replace, replace, replace. All the new vehicles has modules for everything. Easier and more profit to replace things and sell new parts. Unfortunately, engines are becoming quickly lumped into the category of replaceable modules too. Why fix an engine, when someone can replace one for many thousands more than a repair or rebuild?

 

[rockola1971]

I would expect the gauge to read near the middle of the dial (about 210 +/- a couple degrees either side) after maybe 5 minutes tops, unless it is super cold. Then 210 by maybe 10 minutes...

The fact that you are reading 180 after 15 doesn't seem right to me. Maybe just a bad temperature sensor sending incorrect information.

Go ahead and do your pressure testing. No harm in that. Check the levels and looks of the oil, coolant and transmission fluid. If levels hold steady and all look good (not milky, dirty, etc.), I would just change the oil again after maybe 100 miles or so and keep an eye on things. If everything remains unchanged and the oil looks good at that 100 mile change, I don't think I would lose sleep.

If it looks OK (no visible leaks or fluid loss, no fluid cross-contamination), smells OK (no odors up front or at the tail pipe, no sweet smell, no blue smoke or white plumes), sounds OK (no major clanks, bangs, ticks or knocks)...
You might just be OK.

Positive thoughts and fingers crossed!

Mechanics seem to not repair much of anything anymore. Now they want to replace, replace, replace. All the new vehicles has modules for everything. Easier and more profit to replace things and sell new parts. Unfortunately, engines are becoming quickly lumped into the category of replaceable modules too. Why fix an engine, when someone can replace one for many thousands more than a repair or rebuild?

More times than not, it is just more logical and/or affordable to buy a reman engine with a warranty instead of rebuilding what "you" have. Machining and labor costs just arent what they use to be. Parts are much higher too. Look at the cost just for a complete engine gasket kit of a Gen 1 SBC vs a Gen 3/4 SBC. Last time I got a quote at a engine shop it was $80 a hole to bore a block! That quote was like 5 or 6 years ago! I can remember the days of $10-20 a hole. Im with you though....I would much prefer to drop a long block off and get it back from the shop in 3-5 days and start putting it in where it came from myself knowing that the machining guys knew what they were doing and took pride in it while doing it. Like the engine was for their own mom.
Those days just look like they are gone, forever.

 

[01BlueTahoeGuy]

Well I got my cylinder pressure tester today, but as per usual, Amazon strikes again and they sent the wrong Chiltons manual. I have had one for every vehicle I have worked on over the years. They send me the one for the 2007 to 2013 GM trucks, there is only one number different, 28626 (the one I got) and 28625 ( the one I wanted), so will have to re order.

I am hoping to get the testing done on this part of it to get a decent idea where the cylinders are at least.

I will say, I know that prior to it being parked, the maintenance had been done with regular oil changes as well as transmission services.

While I do the compression testing, I will take a peak in the cylinders to check the bores.

I have heard the Vortec’s can go to 250k pretty easily which the right kind of treatment.

I am remaining optimistic that the engine is still sound.

 

[OR VietVet]

You can still run the compression test and hope to see that the lowest reading is at least 80% to 85% of the highest reading. Make sure all plugs are out thru the whole test and disable the fuel system before starting. You can pull the fuel injection relay under the hood in the box. Others here will chime in but I would consider 150 psi as good compression.
IMO, that means the lowest from that 150 high reading, can be as low as 120 psi to 128 psi. But then again, I am a stickler about close readings on the compression test. As smooth as you say it runs, I bet this compression test will be ok.

 

[tom3]

I have used these before with good results. Good read for these here:

Radiator Cooling System Stop Leak Tabs - GM

Radiator Cool System Stop Leak Tabs-gm

www.corvettecentral.com

 

[01BlueTahoeGuy]

Managed to get a coolant pressure testing kit for $40 this week via OfferUp, so I went out today and did a pressure test on the system, it was rock solid at 15psi for 15 minutes with no leaks found.

The oil still looks clean, and it runs smooth with no misses.

I think I will do a cylinder pressure test when I change the plugs and wires.

I know I will have to change the belts to.

Given what I have found so far, I think the engine is good for the moment, so I can focus on other issues, like the Brake Light and the ABS light being on.

As well as getting it cleaned up.

Looking forward to getting it back on the road.

 

[RAMurphy]

There is a good write up and a possible repair to the ABS and brake being on simultaneously on this forum. It includes a video. This may be a solution to that issue.