Hello y'all!

[brad d'Artagnan]

I just inherited a 1978 Birchaven 23 footer! My dad bought it about twenty years ago. Anywho, I've searched through many posts and I have found some really good help that has already made my life easier with my GMC. Thanks for that! I haven't found first what I am about to ask. I know with forums we are sposa search for our questions first before posting. I feel like I've done that satisfactorily.

Now is it true that these GMC's need two batteries to start? I bought an 800 CCA battery from Costco and it only starts one time with the assistance of a jump starter. Then won't restart. Won't crank at all without the jumper (Type S, also from Costco.)

An alternator tester shows the alternator is working. I haven't done the old 'disconnect the battery while it's running to see if it dies' test yet.

I see there are lots of other systems to go through. Right now, it's sitting on slight incline in the dirt. Tires are old yet hold air. The driver side air bag seems like there's a leak somewhere. It's fills with air, but after a couple hours it's flat again. Passenger side seems to hold air. I have not messed with plumbing or house electrical. I'm just wanting to drive it to a place where I can work on it.

Thanks for reading! If you have any suggestions, by all means let me know.

Thanks!

 

[RF_Burns]

I just inherited a 1978 Birchaven 23 footer! My dad bought it about twenty years ago. Anywho, I've searched through many posts and I have found some really good help that has already made my life easier with my GMC. Thanks for that! I haven't found first what I am about to ask. I know with forums we are sposa search for our questions first before posting. I feel like I've done that satisfactorily.

Now is it true that these GMC's need two batteries to start? I bought an 800 CCA battery from Costco and it only starts one time with the assistance of a jump starter. Then won't restart. Won't crank at all without the jumper (Type S, also from Costco.)

An alternator tester shows the alternator is working. I haven't done the old 'disconnect the battery while it's running to see if it dies' test yet.

I see there are lots of other systems to go through. Right now, it's sitting on slight incline in the dirt. Tires are old yet hold air. The driver side air bag seems like there's a leak somewhere. It's fills with air, but after a couple hours it's flat again. Passenger side seems to hold air. I have not messed with plumbing or house electrical. I'm just wanting to drive it to a place where I can work on it.

Thanks for reading! If you have any suggestions, by all means let me know.

Thanks!

There are two battery systems, the chassis battery (starts engine and operates headlights etc) and the house batteries (operates lights etc in the "living" area).

You only need one chassis battery and the 800 CCA should be fine. It sounds like your starter is faulty. Could be bad brushes or worn bearings causing the armature to drag. In any case, you are better to find a business that repairs starters (auto electric business) rather than buying a rebuilt at an auto parts store.

Also, I would avoid the "old 'disconnect the battery while it's running to see if it dies' test". The alternator outputs rectified (pulsing DC) 3 phase AC while the battery acts like big electrical filter (capacitor) to absorb and smooth out the pulses. Disconnecting the chassis battery could cause nasty things to happen.

The air bags have multiple connections and solenoids that could leak. Soapy water from a squirt bottle is your friend to help locate leaks.

Feel free to ask questions!

 

[Bhart]

Congratulations on your receiving a Birchaven.
A must have tool for trouble shooting your GMC is a volt/ohm meter.
Under the passenger side hood, you will see a rectangular box that has fins on it with three or four studded posts (isolator). The center post is hooked up to the alternator and when the engine is running you can check out the output. Select DC volts on meter that has the next higher reading above 12volts. Place your black lead (-) from the meter on a good ground and the red (+) lead on the center studded post. Should get around 14volts.

Another must have is access to the GMC maintenance manuals.
Billy Masey has a website with a whole lot of GMC stuff including links to the manuals for the GMCs.

GMC Motorhome Links

Find MANUALS on the left side and there you will find all of the GMC manuals.

 

[Seeburg220]

Hey Brad - if you haven't already, consider joining GMCMI.com Dues are reasonable and it has many resources, like a parts # exchange list, and pdf back issues of the GMC Vintage RV magazine that has monthly tips and tricks. One of the biggest things they offer, is the Black List - a list of fellow GMC'ers by State with contact info. It could come in handy when you're traveling and have an issue you can't resolve.

Also, join one of the regional clubs of GMCMI and attend the get togethers that these clubs offer, as well as the twice-yearly National rallies. The next one is in Asheville, NC. in April. Camping sites are sold out, but perhaps you could get on a waiting list and you can always just attend without your rv. Nothing cooler than being around dozens and dozens of GMC's all at once. Welcome and good luck!

 

[brad d'Artagnan]

There are two battery systems, the chassis battery (starts engine and operates headlights etc) and the house batteries (operates lights etc in the "living" area).

You only need one chassis battery and the 800 CCA should be fine. It sounds like your starter is faulty. Could be bad brushes or worn bearings causing the armature to drag. In any case, you are better to find a business that repairs starters (auto electric business) rather than buying a rebuilt at an auto parts store.

Also, I would avoid the "old 'disconnect the battery while it's running to see if it dies' test". The alternator outputs rectified (pulsing DC) 3 phase AC while the battery acts like big electrical filter (capacitor) to absorb and smooth out the pulses. Disconnecting the chassis battery could cause nasty things to happen.

The air bags have multiple connections and solenoids that could leak. Soapy water from a squirt bottle is your friend to help locate leaks.

Feel free to ask questions!

 

[brad d'Artagnan]

Hey there! Thanks for the suggestions. If I read you right, a faulty starter could be the reason why the battery gets all used up after one start? I'd never heard that before so it will be welcome news to me. Also if I read you right, only one battery is necessary to operate the vehicle, but a second battery is necessary for cabin lights and stuff not related to actually driving the rig?

As for air bags, I preliminary squirt around the airbag did not show any bubbles. So perhaps there is a crack in an air tube in the cabin or behind the bag? There was a tiny hole in the passenger side fill tube so I cut off an inch of tube and refitted to the fitting. That seemed to be is.

I have not don't the old Disconnect the battery while running test. I am definitely curious if a bad starter is the culprit behind the immediate battery drain.

Thank you very much for chiming in!

 

[brad d'Artagnan]

Congratulations on your receiving a Birchaven.
A must have tool for trouble shooting your GMC is a volt/ohm meter.
Under the passenger side hood, you will see a rectangular box that has fins on it with three or four studded posts (isolator). The center post is hooked up to the alternator and when the engine is running you can check out the output. Select DC volts on meter that has the next higher reading above 12volts. Place your black lead (-) from the meter on a good ground and the red (+) lead on the center studded post. Should get around 14volts.

Another must have is access to the GMC maintenance manuals.
Billy Masey has a website with a whole lot of GMC stuff including links to the manuals for the GMCs.

GMC Motorhome Links

Find MANUALS on the left side and there you will find all of the GMC manuals.

Hey there Bhart! Thanks for chiming in too! Yes I have a multimeter and yes I have factory tech manuals a couple inches thick. I'll def test that charging on the isolater like you detailed for me! Thanks! Very thoughtful!

 

[brad d'Artagnan]

Hey Brad - if you haven't already, consider joining GMCMI.com Dues are reasonable and it has many resources, like a parts # exchange list, and pdf back issues of the GMC Vintage RV magazine that has monthly tips and tricks. One of the biggest things they offer, is the Black List - a list of fellow GMC'ers by State with contact info. It could come in handy when you're traveling and have an issue you can't resolve.

Also, join one of the regional clubs of GMCMI and attend the get togethers that these clubs offer, as well as the twice-yearly National rallies. The next one is in Asheville, NC. in April. Camping sites are sold out, but perhaps you could get on a waiting list and you can always just attend without your rv. Nothing cooler than being around dozens and dozens of GMC's all at once. Welcome and good luck!

Hey there Seeburg220! Thanks for chiming in too! I'm going to look at that web site and check out the local clubs. I'm in Sandy Eggo and the moment and will head back to New Orleans in a short while leaving the RV here until I can come back.

Thanks for the suggestions!

 

[pvfjr]

Welcome!

Is the battery truly getting drained after one start? Can you have it tested for capacity and series resistance? Cheap, portable digital battery analyzers have become prevalent, and can help uncover these mysteries. I suppose we can't assume the battery is perfect just because it's new. Sometimes reasonable assumptions can turn troubleshooting into a nightmare, so trust nothing and verify everything.

Can you leave a good voltmeter attached directly to the battery so you can monitor the voltage? What is it before a start, while it's running, after shut-off, etc?

 

[brad d'Artagnan]

Hello! Thanks for the input.

Sure, the battery is brand new and this is the first install. Just because it's new, doesn't always mean it's good. I have a multimeter and I should meter it before during and after. Thanks! There is also a charger jumper. It shows 14 plus volts charging.

Interesting to note that the RV will not start on just the battery alone. I bought a TypeS jumper from Costco. When I use the jumper it will start but won't restart after I turn of the ignition/key.

Newsflash! The belt for the alternator is in fact broken! How I did not see that until now I'll never know. Though we all know the battery won't charge without a working alternator, that shouldn't have any effect on merely starting from a freshly bench charged battery. No?

I'll replace the belt and hope there will be a significant difference, though I'm not holding my breath. I'll most likely have the starter rebuilt or buy a new one. There seems to be enough symptoms like battery drain on or off and drain just to start one time. If the starter is draining, then one battery should be all that's needed to start and drive the RV, not power all the inside accessories for a camp trip. Yeah?

I'm having trouble finding a starter locally. Is there a cross reference for another GM engine that might be for common? Olds 350 for example.

What say y'all? Sound like a plan?

Thanks again!

 

[pvfjr]

Though we all know the battery won't charge without a working alternator, that shouldn't have any effect on merely starting from a freshly bench charged battery. No?

Correct. You shouldn't need a functioning alternator for starting the engine.

If the battery is truly at full capacity (not just a surface charge) and isn't experiencing excessive internal voltage drop while cranking, then perhaps you have bad connections. The battery and starter cables weren't the best to begin with at a puny 4 gauge, so corroded resistive connections really don't help. Weak and tired starters are also good at drawing amps without turning into mechanical motion effectively. Marginal performance of the starter could be helped a bit by a booster in the right conditions.

Where exactly are you attaching the jump box? To the battery cables at the battery terminals?

 

[pvfjr]

Here's a starter I once bought from Rock Auto. It has performed flawlessly, and it really cranks compared to the old one! You can't beat the price. The whole starter for the GMC was cheaper than just the starter drive for the Corvair you see on the same receipt. Shipping charges weren't bad either, considering what those things weigh.

 

[RF_Burns]

Couple of questions:
-With the single battery (no booster pack connected), When you turn the key to Start, do you hear the loud "clunk" of the starter solenoid? If no "clunk", try moving the shifter lever or move the shifter to Neutral position, the Neutral Safety Switch could be faulty or miss-adjusted. If you hear a "Clunk" but the starter does nothing, then the starter solenoid may be faulty or have a bad connection to the starter terminal.

-Turn the headlights ON and have someone stand outside and watch them (or do this test a night). With the headlights ON, and you turn the key to Start, do the headlights stay bright or do they dim out to nothing or very dim? If the headlights dim out, then you have a bad connection, faulty battery or the starter is stalled and drawing excessive current. If they stay bright, then the starter is not drawing any current.

If the starter bearings are worn, then the armature can drag on the field coils and not turn. Adding a booster could give enough current to get the armature spinning.

Just this ex-farmboy shade-tree mechanic's 2 cents.

 

[brad d'Artagnan]

Welcome!

Is the battery truly getting drained after one start? Can you have it tested for capacity and series resistance? Cheap, portable digital battery analyzers have become prevalent, and can help uncover these mysteries. I suppose we can't assume the battery is perfect just because it's new. Sometimes reasonable assumptions can turn troubleshooting into a nightmare, so trust nothing and verify everything.

Can you leave a good voltmeter attached directly to the battery so you can monitor the voltage? What is it before a start, while it's running, after shut-off, etc?

Thanks for chiming in! Since my first post, I've discovered a shredded alternator belt. Obviously charging is non existent however even if the alternator was working fine, it doesn't seem likely that it would be responsible for not getting more than one start out of a freshly charged battery. Right?

Now I'm having trouble sourcing an alternator belt for my 23ft Birchaven. I believe it's a 403 engine. Neither AutoZone nor O'Reilly has a belt long enough to fit. Any help finding one will be appreciated.

I'll check the voltage on the battery with. Multimeter, though the jumper charger says the battery was charging at 14 15 volts at 16 amps. Gets plenty of charge, just gets depleted swiftly. Like other commenters, it's seems plausible that the starter is bad and is the reason for the drain.

Thanks again!

Here's a starter I once bought from Rock Auto. It has performed flawlessly, and it really cranks compared to the old one! You can't beat the price. The whole starter for the GMC was cheaper than just the starter drive for the Corvair you see on the same receipt. Shipping charges weren't bad either, considering what those things weigh.

View attachment 12542

Thanks! Do the 403 and 455 engines use the same starter?

 

[tmsnyder]

Thanks for chiming in! Since my first post, I've discovered a shredded alternator belt. Obviously charging is non existent however even if the alternator was working fine, it doesn't seem likely that it would be responsible for not getting more than one start out of a freshly charged battery. Right?

Now I'm having trouble sourcing an alternator belt for my 23ft Birchaven. I believe it's a 403 engine. Neither AutoZone nor O'Reilly has a belt long enough to fit. Any help finding one will be appreciated.

I'll check the voltage on the battery with. Multimeter, though the jumper charger says the battery was charging at 14 15 volts at 16 amps. Gets plenty of charge, just gets depleted swiftly. Like other commenters, it's seems plausible that the starter is bad and is the reason for the drain.

Thanks again!

Thanks! Do the 403 and 455 engines use the same starter?

Check on RockAuto, look at starter part numbers for a 73 Olds Toronado vs a 78 Olds Toronado

You can also get a like year starter from a RWD Olds full size car with same engine and swap the snouts on the starter. The RWD versions are much more common, they may even have them in stock.

Best bet however, is to take your starter to a shop and have it rebuilt with quality components. Same for alternator. Same shop will do both.

 

[timthenomad]

Hi Brad.

I have the same model you have-- a side bath Birchaven. The finest of the models if I do say so.
So if your battery system is stock (and that is a really, really big if) you will find that you have 1 starter battery and 2 coach batteries wired in parallel. I've found that if either of the coach batteries is faulty I tend to see things like shredded alternator belts, cooked alternators and weird chassis electrical problems.

Coachman put one house battery next to the starting battery up front and second in a vented compartment underneath the rear drivers side bed plywood, which is screwed in with like 8 screws. When I finally found mine it was a dried up Sears Forever Battery from like 1978. A lot of helpful people suggested different ways to re-wire things but I ultimately got to 2 identical glass mat batteries (no water to mess with) and put them in. I've had 5 years of house and chassis electrical peace since then.

On my coach I've found that if I allow any one of the three batteries to die of natural causes, it always takes the belt and alternator with it. I wish that when I first got mine, I had known there were 3 batteries and that I had replaced the whole set. It would have made it easier to move on and deal with all the problems in the fuel system.

Best of luck.

--tim

 

[brad d'Artagnan]

Hi Brad.

I have the same model you have-- a side bath Birchaven. The finest of the models if I do say so.
So if your battery system is stock (and that is a really, really big if) you will find that you have 1 starter battery and 2 coach batteries wired in parallel. I've found that if either of the coach batteries is faulty I tend to see things like shredded alternator belts, cooked alternators and weird chassis electrical problems.

Coachman put one house battery next to the starting battery up front and second in a vented compartment underneath the rear drivers side bed plywood, which is screwed in with like 8 screws. When I finally found mine it was a dried up Sears Forever Battery from like 1978. A lot of helpful people suggested different ways to re-wire things but I ultimately got to 2 identical glass mat batteries (no water to mess with) and put them in. I've had 5 years of house and chassis electrical peace since then.

On my coach I've found that if I allow any one of the three batteries to die of natural causes, it always takes the belt and alternator with it. I wish that when I first got mine, I had known there were 3 batteries and that I had replaced the whole set. It would have made it easier to move on and deal with all the problems in the fuel system.

Best of luck.

--tim

Thanks Tim! I'm going to have a look see toward the rear for that third battery. That would make sense as to why I found an extremely long ground wire headed back that way. Since I'm going to have to put up the coach in temporary storage, I'll just have to use the one battery for driving to the storage space and not plan on any cabin electricity. I'll disconnect the other batteries. Hopefully that's acceptable to let the coach sit with no batteries at all. I'm going to take out the starter batter and use it in my Westfalia. Taking her across the southwester states soon.

Thanks again!

 

[brad d'Artagnan]

Y'all: New starter seems to have fixed it! That must have been where the drain was. I got a rebuilt one from a shop. He swapped in my solenoid with a body that he rebuilt for sixty bucks. I installed it and boom, started right up. Shut it down and then restarted like it's supposed to. This coach has been sitting so long. Tranny seems kinda stiff, brakes seem kinda weak. Lord knows what else needs attention. In time I'll have to go through lots of things.

Thank you for the winning suggestion RF_ burns!

Thanks alla y'all!