Chevy Engine running strangely

[TXbound]

The coach is a 97 Adventurer the engine is Chevy 454 7.4 L Vortec block with 95k original miles I live in it, having an issue that might be a blown head gasket or worse and I really need to deal with it before the next bad storm that may force us to evacuate. Check Engine light not on, can't run OBD2 says its either not connected or the ignition is not on, first thing thar comes to.mind is bad ECM? Bad Sensors? Bad EGR valve? 1st noticeable symptom is white smoke from the manifold, no trace of sweet smell, I took video of it I'm trying to figure out how to share it (no smoke or sweet smell from rear exhaust, only droplets of water, (moisture in the fuel lines is common here, I add a bottle of HEAT and seams to keep it in check) 2nd is had a back fire 1x but started up rough, high idle to almost stall till it warms up than it revs high and than adjusts to close to normal idle. It hasn't had a tune up in years, there is a presence of oil on the engine cover near spark plugs manifold side. No sign of coolant leak, I did the trick to take the coolant cap off before starting and as soon as I started it in less than a minute it overflowed bubbling, I understand that could be a sign of a blown head gasket. Any thoughts on what's going on and what I can do to prevent any potential further damage? Thanks

 

[B52Bombardier1]

Hello,

Lots going on here. What do the spark plugs look like? Sooty, black and oily?

No OBD2 could be a bad fuse for power to pin 16 - at least in car PCM devices. I would not say bad PCM at this point, these things are quite rugged and dependable. Use a multimeter set to DC volts and check for power on pin 16. Check the owners manual to see what fuse controls pin 16.

A quickly bubbling and overflowing radiator reservoir tank is . . . yea, probably a blown head gasket. Put some UV dye into the radiator and use the UV light and goggle kit to see if the dye eventually appears in the tail pipe moisture. There are two ways to fix this and one method is expensive and the other is controversial. Its either do it by replacing the head gasket if the vehicle is worth it or use one of the Bar's Stop Leak or Blue Devil Head Gasket Repair fluids.

Your varying idle speed is telling me that you have an intake manifold vacuum leak.

It sounds like your vehicle is going to need some attention from a mechanic but none of these appear fatal to the engine at this point.

Rick

 

[Jabber Jaw]

Good advice from "Rick" in the above comment.

I'll add to that and recommend you contact "Ultra RV", as they seem to have a lot of knowledge & technical info on the Workhorse chassis & the 8.1 V-8 that came in them.
Check the link below for their contact information.

www.ultrarv.com

Good Luck

 

[TXbound]

Hello,

Lots going on here. What do the spark plugs look like? Sooty, black and oily?

No OBD2 could be a bad fuse for power to pin 16 - at least in car PCM devices. I would not say bad PCM at this point, these things are quite rugged and dependable. Use a multimeter set to DC volts and check for power on pin 16. Check the owners manual to see what fuse controls pin 16.

A quickly bubbling and overflowing radiator reservoir tank is . . . yea, probably a blown head gasket. Put some UV dye into the radiator and use the UV light and goggle kit to see if the dye eventually appears in the tail pipe moisture. There are two ways to fix this and one method is expensive and the other is controversial. Its either do it by replacing the head gasket if the vehicle is worth it or use one of the Bar's Stop Leak or Blue Devil Head Gasket Repair fluids.

Your varying idle speed is telling me that you have an intake manifold vacuum leak.

It sounds like your vehicle is going to need some attention from a mechanic but none of these appear fatal to the engine at this point.

Rick

Hi Rick, I haven't checked the plugs yet I will check them today and get back to you , I just read on that the test for the bubbles, should be done with the engine cool, tries that mean with the engine off? I should have mentioned I can hear vacuum like sounds like air is being sucked in from somewhere, for what it's worth it has cruise control The other things sounds pretty straight forward to test, I'm getting 12 volts at PIN 16, same at ECM fuse, was easy to find it's labeled on the fuse block, the thing that's throwing me is the OBD does diagnose it just does it faster than my mini van, I'm wondering if my OBD2 scanner might not be compatible with this ECM, I took some photos of the results and will upload them as I can, although one does say fail the component ID $0c indicates a misfire but that is all the info I could find for that. I jumped the gun and yesterday I added some Bar's Leaks High Mileage Engine Repair, I hope it's not too late and the head gasket doesn't have to be replaced I know it can be a somewhat labored job and I'm not about to tow the rig to the shop while we are living in it, I .might have a mobile mechanic that might be able to do it, either way I need to do something before the threat of storms is on us. Thanks Ken

 

[TXbound]

Surprising update, I had the dog house open, I was looking to take off the plug wire which seems a task in itself, when I dropped a wrench on the ground, below the drivers side lay a short hose as you can see in the first picture, I almost blew it off, but something told me to pick it up and see if it goes to the engine, sure enough,it was missing I put it on as you can see in the second picture I put back thinking to myself it can't be that simple, in the hopes that it would change something, said a short prayer and fired it up and sure enough no more high idle to stall, smooth as butter it's obviously a vacuum hose, that have been disconnected and u probably just knocked on the floor today, I don't know why it got disconnected and I'm still going to have to figure out what the smoke from the manifold is about but at least I don't have that vacum issue to figure out.

 

[TXbound]

Surprising update, I had the dog house open, I was looking to take off the plug wire which seems a task in itself, when I dropped a wrench on the ground, below the drivers side lay a short hose as you can see in the first picture, I almost blew it off, but something told me to pick it up thimking i may accidentally disconnected it, and see if it goes to the engine, sure enough,it was missing I put it on as you can see in the second picture I put back thinking to myself it can't be that simple, in the hopes that it would change something, said a short prayer and fired it up and sure enough no more high idle to stall, smooth as butter it's obviously a vacuum hose that loosened, I don't think I accidentally disconnected it since this is the first time I've had the dog house open in months and the symptoms started a few days ago.I It was probably off and when I opened the dog house it fell.off. I'm still going to have to figure out what the smoke from the manifold is about but at least I don't have that vacum issue to figure out.

 

[TheLooks]

Before you throw lots of money into it, a simple tune up might be in order.

 

[TXbound]

Agreed, I think I need to buy a maintenance. manual

 

[TXbound]

Got some good news and bad news, bad news first I broke a bolt, good news one of the bolts to the manifold was loose, as you can see in the picture it's the one on the left, unfortunately, the bolt that broke may be related to the manifold or it's just to hold the plug wire in place as there is a bolt on each fitting that goes around the wire. More bad news, the smoke is coming from under the plug chamber, more good news tried the radiator trick again nothing came out of the radiator. I'm already thinking about extraction, not the easiest spot to get to with a drill, or try to JB weld the head to the bolt providing there doesn't need to be much torque, but if it's related to the manifold, I would think the torque needs to be high. Any idea if it's for holding the manifold, my guess is the bolt is so rusted in it's not going anywhere.

 

[TheLooks]

That is a manifold bolt and you will likely break more then one by the looks of them. Snap them off, take the heads off, take them to a machinist, have them rebuilt and get the studs out, and put new bolts in. That will take care of the white smoke most likely. When things are let go that long, it costs money. Although the Ram bolts are breaking without the corrosion now a days.