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2000 Chevy 3500 Slumber Queen! - So many Symptoms

Hey!
I have a RV. Its built on a Chevy 3500 Slumber Queen. Its got a few minor issues that I feel are pointing to possibly one issue. Not sure but hopefully you can help me diagnose. I’ll try and describe everything and its history so that you can get a full picture of what is going on.

So about 6 months ago the vehicle had a stutter. It would only really happen while maintaining a speed going uphill. It also started poorly in the mornings. I had a mechanic look at it and confirmed we were loosing fuel pressure over night. I ended up changing the Fuel Pump and filter in a “Canadian Tire” parking lot. That was fun. The vehicle seemed better after that for a few months.

Then! A few months later we started experiencing the stutter again. So took it into a mechanic again and they slapped a Scanner on it and decided to clean and change some sensors. I’m no mechanic and I would have to figure out which ones exactly they changed but I believe it was the MAF and O2? One was cleaned and one was replaced. Don’t know how much that really changed.

Now we still have the stutter. Like I said it only happens at higher speeds and seems somewhat random. Could be on a hill, could be while accelerating, could be while maintaining speed.

The poor start has also come back with a vengeance. It’s starting to get a little colder up here in Canada and that seems to make the start worse. It turns over well but seems like it might have trouble sparking? I have been told the spark plugs look newish. I also tested the battery it read 12.6 before starting and never dropped below 10 while starting.

In addition to all of this I have other problems that may give hints to the issue and also could be totally unrelated. The coolant sloooowlly disappears. Where it goes I don’t know. But what is in the reservoir will slowly go down over the course of months. Also after a long drive when we shut off the vehicle you can hear a gurgling inside the passenger side glove box. Sounds like hot liquid. I have read that this is normal, but doesn’t sound normal haha.

Anyways a lotta information there. Hopefully it’s useful in helping me figure this out. I was thinking about buying a scanner and thought that might give me some info. But I have never used one so I thought I might just be looking at numbers not knowing what to do with them. Any help is appreciated! Thanks!

ill try to describe everything in detail. oof. you almost lost me there
3 things. canada. cold. Rv.
do you have to drive this RV in the winter? shouldnt it be in storage?

haha Currently living in it actually. Don’t know how long I’ll last but average lows of 3 mid-Winter in Vancouver shouldn’t be too bad.

what type of ignition system does this have? coils? module? distributor? or no?
critters chewing on some wires?

Hmm, I am not certain. As I said I am not mechanic. Is there an easy way to identify which system it is?

Before worrying about anything else, figure out where the coolant is going.

If the coolant gets low enough, air can collect in the heater core because it’s the highest point of the cooling system. The bubbling you’re hearing is in the heater core behind the glove box.

Have someone connect a cooling system pressure tester to the system to see if the leak can be located.

Tester

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an RV could have a hot water loop to the rear storage tank for the shower/bath. lots of places to leak. the motor could be like a 2000 truck. it might have a throttle body. not even sure what size we are talking about. it could be a 350 or even a 454.

Huh?..

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I wonder if coolant is leaking into one or more of the cylinders. I had the same symptoms on a 1990 Ford Aerostar I once owned. The problem turned out to be a cracked cylinder head. Fortunately, the Aerostar was still on warranty.

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I’m also thinking coolant is entering the cylinders (via an unknown path at this point) and sometimes putting out the spark, causing intermittent misfires. Any signs of white smoke/steam coming out the tailpipe? Ask a friend in another car to follow you as you accelerate 0-60 rapidly up a freeway on ramp, looking for white smoke from your tailpipe. Another idea: Remove the spark plugs, any of them look steam cleaned?

Chevrolet V8 and V6 engines of this era had issues with leaking intake manifold gaskets. My 2000 Blazer needed a new gasket not long after I bought it in 2003. A slow drop in coolant level is one of the symptoms.

Ed B.

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You need to tell us EXACTLY which GM engine you have

V6 or V8

gasoline or diesel

exact engine displacement . . . 4.3 5.7. 6.0 7.4 or what have you

@db4690 it is the V8 5.7 L Gas
@edb1961 interesting…ill try and look into this.
@George_San_Jose1 I have white smoke/steam on start up but it seems to fade away as the engine warms up. Would buying a scanner help me diagnose this? By steam cleaned you just mean really moist?

one more thing I was climbing a steep hill today and noticed that it had an odour to it. it never really overheats but will smell sometimes while working hard.

Thanks everyone for helping out.

Your engine is well know for lower intake manifold gaskets degrading, to the point that coolant finds its way into the crankcase . . . which could conceivably lead to white smoke

Leaking lower intake gaskets would also go a long way towards explaining where the missing coolant went . . .

Your particular fuel system also has well known “issues” . . . to put it nicely. It’s possible that the fuel pump is fine, but that your pressure loss is occurring in the engine bay. Under the plastic upper plenum is the central injector, along with 8 poppet nozzles, nylon fuel lines, and a fuel pressure regulator assembly. This should be easy for a competent . . . I hate to say it, but there’s plenty of guys who don’t fit that description, no matter how long they’ve been turning wrenches . . . mechanic with a pro-level scanner to figure out.

No, not moist, but looking really clean, almost like new. If the tip of one spark plug looks much cleaner looking than the others, like it just came out of the dishwasher say, that’s an indication coolant is getting into the cylinder. For normal spark plugs, after they’ve been installed awhile then removed, their electrodes will have some noticeable brown, black, grey, and/or reddish deposits on them.