Offroad Trailblazers and Envoys

Intermittent Engine Power Loss and Stalling at Stops

Something not working right?

by Trail X » Thu Jun 08, 2017 9:10 pm

Coming back from TECORE, I was getting some codes relating to an issue with the camshaft position. I knew that the CPAS was fairly new, so I thought that the oil must be getting old, or maybe some chunks of old gummed up oil got loose. I don't really drive the TB very often anymore, so I figured the oil was about a year old, and it was time to change it.

I had the idea in my head that Seafoaming the crankcase before I changed the oil would be a good idea just to knock out any potential gummy oil that might be hanging around the CPAS.

Yesterday I put the seafoam in, and drove to work and back, ~30 miles. No issues. Today, I was on my way to work and the engine started surging on the interstate. It stalled when I came off the exit ramp. Odd, last time that happened I had an O2 problem and a cracked manifold. Started back up fine, but wanted to either high idle, or it would want to stall. It would have intermittent bouts where it would put out significantly less power, then all the sudden it would restore to full power.

I started putting two and two together - generally if you get bad symptoms so quickly after you change anything - reconsider what you just did. Coming home from work was ok at first, then once again started surging, losing power, and finally died again. This time, when it died at a stop light, it chugged down to about 100 rpm and the DIC informed me of the low oil pressure, and that I needed to stop the engine. Crud. Limped it home. Changed the oil. I crossed my fingers that it would be end of it.

:mechanic:

Now its worse than before. I can't drive around the block without it stalling, and I'm pretty sure its due to low oil pressure.

I'm thinking that the oil pickup is clogged with the shit that fell out of the engine while the Seafoam solvent sat on everything overnight. Seafoam apparently also has the effect of thinning out the oil. So when I drained it, it almost looked and splashed more like water instead of oil. Now that I have new oil in there, its more viscous, and therefore is having even more trouble fitting through the restrictions.

First, a lesson - if you haven't been using Seafoam in the crankcase since the engine was low mileage - don't start.

Second, a plea - does anyone have some direction for me? I'm leaning towards dropping the pan, dropping the oil pickup, and doing my best to clean that all out. Hopefully the restriction is somewhere in the pickup tube. If its not, I'm not entirely sure how to service it. I guess at that point it would be time to take out and clean the oil pump. Any other advice or thoughts?

:facepalm:
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by NC_IslandRunner » Thu Jun 08, 2017 9:22 pm

I would drop the pan, the cleaning additives may work but not worth the risk of damage to the engine.
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by Anthony Hernandez » Thu Jun 08, 2017 10:36 pm

Damn bro, let me know if you need help. I have a motor and pcm on my porch. Just in case. I've put oil in it and turned it regularly.
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by larryk » Thu Jun 08, 2017 11:07 pm

How's the compression.... and can you turn the engine by hand using the belt? While low oil pressure is not a good thing, shouldn't make the engine stall or run like crap. Those are signs of bigger problems.... ie seizing engine :(

Never ever ever run an engine under load with seafoam or any other cleaner in the crankcase. As you noted, the oil thins out, and isn't designer to carry a load. I doubt there is crap in your pickup, as the seafoam "melts" the build-up, doesn't break it up into chunks.

Good luck
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by Trail X » Thu Jun 08, 2017 11:22 pm

Yes, unfortunately the seafoam bottle says nothing about not running the engine under load. In fact somewhere it says to run it for less than 100 miles.

The engine seems to run fine at first on cold start, but eventually tries to die. On the interstate it wasn't continual low power output, it would go fine for a bit, then you'd feel the power dissipate as you demanded more power from a lower rpm. Seemed like the oil pump is what was starving. When it would die, there'd be a squeaking noise like the belt slipping slightly. I believe the oil pump is tied to the water pump shaft, I think, so if it was killing the engine, it makes sense for the belt to be under a ton of stress.

I can check to see if the crank turns with a wrench. I don't think I've ever been able to turn the engine by just pulling the belt with my hand. Plus, why would Seafoam cause the engine to seize? What's the mechanism that would cause that?

There's also a crazy thought floating around my head that maybe I should try seafoam again and seeing if it breaks up any of the remaining sludge that's blocking the system somewhere. Probably stupid, but, if I drop the pan to replace the oil pickup I'll lose the oil I've got in there anyway.
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by mason10198 » Thu Jun 08, 2017 11:30 pm

If you end up dropping the oilpan and cleaning the sump out, just use some diesel instead of any cleaners. When I did everything to my new motor before putting it in, I dropped the pan and cleaned it and the sump. I just filled a bowl with diesel, and let the pickup sit in it for a few minutes before pouring it through the tube back and forth a few times to rinse the crap out. Then I just blew it out with an air compressor and it was nice and clean.

Edit: I also used a wooden toothpick to push the little gunky bits out of the mesh at the end of the pickup

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by larryk » Fri Jun 09, 2017 6:26 am

Oil pump is a gerotor style that's actually attached to front of the crank, with the housing part of the front cover. The squeaking, unfortunately,could also be a bearing going bad. Back in the day, I lost a small block with those symptoms. When cold, ran great.... once it's heated up, tightened and ran like turd. Also made a squeaking noise as the bearings were seizing up.

I hope for the best..... but I'm not optimistic. :(
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by bartonmd » Fri Jun 09, 2017 7:53 am

Squeaking is likely a bearing, as mentioned above. Less oil, and less boundary layer from the Seafoam in it. I've never heard of actually driving with seafoam in the oil. I'd heard to warm up the engine, put the seafoam in, let it idle for a bit, maybe rev it some in park, then shut it off and let it sit a day. Next day, start it and run/rev it in park to knock loose the stuff that got softened over night, then shut it off and drain the oil and change the filter. Seafoam is mostly alcohol and light oils, so it breaks up oil pretty well, meaning that it also doesn't let the oil work well as oil, under load.

If you had been running synthetic this whole time, I can't see there being that much to break free, though, because the additive package in synthetic oils is so strong.

Personally, I'd drain the oil though a strainer and see what comes out. If you've got chunks of shit, I'd probably fill it with trans fluid and idle it for a while. Trans fluid is meant to last a long-ass time, so it's got a ton of solvents in it. Other than that, I'd throw some marvel mystery oil (lots of solvents/oils, but less alcohol than seafoam) in it or something, to see if it'll break up the stuff that's stuck to the pickup screen. Like start it and let it idle for a minute, then shut it off and let the additives work for a day or 2.

Barring that getting it back to normal, you've likely spun a bearing or something, and are looking at a junkyard engine, but take the oil pan off to make sure the pickup just isn't just plugged still. Actually, if you're having the problems and sounds that you're talking about, and for the time that you're talking about, the damage is likely already done.

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by Trail X » Fri Jun 09, 2017 8:30 am

larryk wrote:Oil pump is a gerotor style that's actually attached to front of the crank, with the housing part of the front cover.

Crap, I misread the schematic. Yeah that wouldn't be as easy of a fix as I originally thought.

Cold, it seems to idle fine, but a wrench on the fan pulley will not turn it over, the fan pulley slips on the belt. At idle, the throttle position is at about 12-18%, doesn't really imply that its seizing right? That's all I had time to look at this morning.

bartonmd wrote:Squeaking is likely a bearing, as mentioned above. Less oil, and less boundary layer from the Seafoam in it. I've never heard of actually driving with seafoam in the oil. I'd heard to warm up the engine, put the seafoam in, let it idle for a bit, maybe rev it some in park, then shut it off and let it sit a day. Next day, start it and run/rev it in park to knock loose the stuff that got softened over night, then shut it off and drain the oil and change the filter.

I was just trying to follow the directions from Seafoam. https://seafoamsales.com/how-to-add-sea ... crankcase/

bartonmd wrote:If you had been running synthetic this whole time, I can't see there being that much to break free, though, because the additive package in synthetic oils is so strong.

I've been running full synthetics since 50k miles on the clock. Its got ~180k-190k now. Although, the engine has always seemed to run a little hot - ~230F coolant was common on longer drives. So that could have caused some sludge.

bartonmd wrote:Personally, I'd drain the oil though a strainer and see what comes out. If you've got chunks of shit, I'd probably fill it with trans fluid and idle it for a while. Trans fluid is meant to last a long-ass time, so it's got a ton of solvents in it. Other than that, I'd throw some marvel mystery oil (lots of solvents/oils, but less alcohol than seafoam) in it or something, to see if it'll break up the stuff that's stuck to the pickup screen. Like start it and let it idle for a minute, then shut it off and let the additives work for a day or 2.

I've got some full synthetic high mileage oil in it right now. So far I drove it around the block yesterday, and it wasn't happy. I ran it a little this morning, hoping that maybe letting the new oil sit will help. I understand that the high mileage oil has extra solvents and wear additives that could help.

bartonmd wrote:Barring that getting it back to normal, you've likely spun a bearing or something, and are looking at a junkyard engine, but take the oil pan off to make sure the pickup just isn't just plugged still. Actually, if you're having the problems and sounds that you're talking about, and for the time that you're talking about, the damage is likely already done.

Yeah, I was afraid of that. Dropping the pan on a 4WD TB is a lot of work that I don't have the time for right now.

Anthony Hernandez wrote:Damn bro, let me know if you need help. I have a motor and pcm on my porch. Just in case. I've put oil in it and turned it regularly.
Your truck is a 2006+ right? What year is the motor?
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by bartonmd » Fri Jun 09, 2017 9:21 am

Yeah, I suspect you're looking at a shit sandwich any way you cut it, right now.

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by HARDTRAILZ » Fri Jun 09, 2017 12:27 pm

That sucks for you James. I hope you can fix without a full swap.
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by Trail X » Fri Jun 09, 2017 3:58 pm

I sent in a note to Seafoam's website today, and was surprised to get a call back from them this afternoon. They seemed concerned about my predicament, but were adamant that in their experience, Seafoam in oil has never been the cause of these symptoms. Their suggestion was to start troubleshooting this as if the Seafoam treatment was not a factor before concentrating on the oil itself.

Some of the other gearheads here at work agreed that this didn't seem like it was specifically an oil related issue, and that it may be somehow coincidental. So my first task will simply be to clean the throttle body and the crankcase vent. The thought there is that Seafoam might have created extra carbon burn off, which caused faster than normal buildup on the throttle plate which the PCM was unable to adjust to, possibly even clogging the vent. So I'll start there.

I've also got one of those bluetooth OBD sensors coming tomorrow which may help with some diagnosis of the fuel trims (I can't believe I haven't gotten one of these before). Bummer that the oil pressure sensor is a toggle and not an actual sensor that can be read.
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by CHEVELLE598BB » Fri Jun 09, 2017 6:40 pm

I would like to see what codes it's throwing right now. Then scan pids to see what live data is doing.

Sure does sound like a bearing problem though. Been there a few times.

Maybe I'll try a little seafoam so I can get my 5.3 swap started.
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by larryk » Fri Jun 09, 2017 7:31 pm

Ok....even if the throttle blades are gummed up, or your pick-up is plugged, symptoms are of bad bearings/ seizure. Whether it's from the seafoam or plugged pickup, it still sounds hosed.
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by Trail X » Fri Jun 09, 2017 10:34 pm

You guys may be right. I am not familiar with the sound of lower end knock. Listening well, I noticed the following two noises appear once the engine got up to temperature.

This one is one I think I've heard before, but not often. Maybe I heard it during the last TECORE. I can't say that I recognize what it is though. Video taken from the driver side wheel well.



This one isn't one I've heard before, but I'm afraid it may be a bearing knock. Video taken from behind the engine, around the transmission.



Hope someone that has more experience can help me better identify the noises. The noises are actually more clear on the video than in person. They are pretty faint in person.
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by v7guy » Mon Jun 12, 2017 2:48 am

I've munched a couple motors in my time, the surging,dying,power loss and random power recovery, especially when coupled with a squeak, all sound like spun bearings to me. They're the exact symptoms I had on both motors I spun bearings in.
You get low oil pressure when the bearings rotate, and you get a random squeak sound that comes and goes as they randomly rotate, etc etc etc
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by Trail X » Mon Jun 12, 2017 8:39 am

I'm still not ruling out a fuel delivery problem. I've read that a weak fuel pump can also contribute to very similar symptoms due to fuel vaporization in the rail. Maybe unlikely, but I can hope. Hoping to get a fuel pressure gauge on the rail this evening.

Anyone have a clue about the first sound posted above?
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by bartonmd » Mon Jun 12, 2017 4:03 pm

I don't hear much of anything other than normal stuff in the first one, but I'm listening in headphones that are kind of tinny, so I wouldn't hear any low end stuff. The second one, I hear a little bit of low end knock.

The other part of it is that the L6 is pretty susceptible to low oil pressure on steep climbs, so you could have been doing some damage all along, and just thinning out the oil to a 15-20W instead of a 30W was enough to break down the hydrodynamic bearing surface.

I'd believe fuel or TB issue if it was just surging, but the squeaking when it does it sounds like a spun bearing to me. Hoping it's not, but who knows...

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by navigator » Mon Jun 12, 2017 4:40 pm

Could the seafoam/gunky oil have caused one of the sensors to go haywire and cause some of the symptoms you are seeing? Have you checked that camshaft position actuator screen or whatever it is called? I've run the seafoam in my TB crankcase before, like 1/3 can for a few minutes until it warmed up with no issues. In my suburban, I drove the 15 minutes home from the parts store with no issues. In both cases the oil looked like coffee running out. Just curious if it killed a sensor or something. Seems changing those sensors caused mine to run rough for a bit as it did a relearn, if the sensor was hosed it might give the symptoms longer. I had none of the squealing noises you mentioned though.
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by KingBird » Mon Jun 12, 2017 6:33 pm

Yeah, that's exactly how mine acted before it gave up and finally locked down.

I have yet to rip it apart, but I suspect my oil pump failed or my sump tube fell out..

I don't have a clue, but it sounded exactly like that.
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