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Jenniflow · 10-19-2013, 03:42 PM

Hi folks,
I have a 1986 345 Moho that we are just starting to use again after about 6 months. She is doing greet so far except that she is stalling several times when I first start her up, even if I let the engine warm up for 10 minutes first. The oil pressure light comes on and I am standing in the brake.

If I let it warm up for 25 minutes this tends not to happen but at this point I'm not really that sure that's the factor of most relevance.

I have several questions. If you have any thoughts I'd appreciate it:

1) what could be going on?
2) what is the best oil for this engine pulling 34.5 feet of coach? We live in northern CA where the temp occasionally dips below freezing during long periods when the Moho is stored.
3) should we use different weight oils in the winter and in the summer?

Thanks!
Jenniflow

cwf · 10-19-2013, 03:47 PM

My thought is bad fuel. How full is tank? Can or have you put additive,?

TomW · 10-19-2013, 04:03 PM

Quote:

Originally Posted by Jenniflow

... she is stalling several times when I first start her up ...The oil pressure light comes on ...

1) what could be going on?

2) what is the best oil for this engine ...

1) The warm-up throttle setting is way too low. But with a cold engine, the oil pressure light coming on means either a worn sensor or tired engine.

2) I used 10W-40 in my 454 engine (the same one you have) year around.

Tom

Waipio Rim · 10-19-2013, 04:20 PM

If the idle speed drops too low for awhile on the way to the engine quitting, oil pressure will drop and the light will come on. This will hopefully go away once you get the problem fixed.

Sounds like a bad fuel or carburetor problem. If it does not improve as you get rid of the old fuel and/or you don't know when the carburetor was last rebuilt, look around for a mechanic who is old enough to know how to rebuild a Quadrajet carburetor. Our gas mileage improved by about 40% when we had ours rebuilt.

Phoenix · 10-19-2013, 09:46 PM

Above suggests are all good ones. Problem sounds like a sticky or improperly adjusted choke, or a possible sticking or defective carburetor float or bad valve/seat (assuming your engine is carbureted).

When we had our 454 rebuilt (in a 1978 Chevy crew cab pickup), we ran straight 20W for awhile, per the rebuilder's recommendation for Phoenix, AZ (110+ desert heat in the summer and a few nights in mid-20's in the winter). However, after the first year, I switched to 10W-30; and later to 10W-40 (for convenience, since our other cars used 10W-40). For northern California, I'd use 10W-30.

Also, just my opinion, but I'd use regular Castrol, Quaker State or Pennzoil and NOT synthetic oil; and change it at 3-5,000 miles. 454's can be hard on oil; and while synthetics will last longer, they can also tempt you to stretch the time between oil changes. It's safer to change your oil more frequently; and you won't feel so bad about changing it, if you aren't paying premium prices for synthetic.

Jenniflow · 10-20-2013, 09:48 AM

These are great suggestions, thanks! I suspect it is related to the carburetor since it's never been rebuilt. I'd love to gain some efficiency, while we're at it.

The gas I'm using is about six months old and though I did add a couple of bottles of dry gas to the approx 40 gallons of gas that were in the tank, I was adding it to the top. I don't know how well dry gas mixes on a short sprint to our current location.

I should probably take her for a longer drive to test it but it's Sunday and I can't take her in for service today if something goes more wrong. My main goal is to move her from one space in a cAmpground to another where I'll be storing her for another six months, having lived in her for one.

I will certainly look around for someone who knows quadrajets. Maybe I should try the VA retirement home! ;-))

I just remembered that I have about six bottles of that Shell Oil in one of the compartments. I bet it's over ten years old! (Long story). I'm also betting I can't use that any more, right? And I wouldn't want to add any of it in top of whatever's in there now? (I have to check with the garage that changed the oil in March.)

Thanks again!
Jenniflow

Punch · 10-20-2013, 10:19 AM

Quote:

Originally Posted by Jenniflow

I will certainly look around for someone who knows quadrajets. Maybe I should try the VA retirement home! ;-))

Jenniflow

I take it you're not mounting a charm offensive.

Jenniflow · 10-20-2013, 01:01 PM

Ha! No, I'm getting close to retirement age myself! Last time I took this coach to a garage, the (young) mechanic looked at it, stroked his chin thoughtfully and said, "Yeah there was some old guy used to come around here who knew these engines. Maybe we can get him for you?"(!!)

cwf · 10-20-2013, 03:58 PM

Us "old QUadrajet guys" are still around. There will be some "hot rod" shops with ancient Talismans to recover your lost mojo.

ROBERT CROSS · 10-20-2013, 06:02 PM

If are enamored of the Q-jet, get it done right......OR..

After carb work and BEFORE starting. Replace all fuel filters and inspect lines, consider flushing/sealing or replacing gas tank.

You could always replace it with a newer up-grade.

Bob

Punch · 10-20-2013, 07:37 PM

Quote:

Originally Posted by ROBERT CROSS

If are enamored of the Q-jet, get it done right......OR..

After carb work and BEFORE starting. Replace all fuel filters and inspect lines, consider flushing/sealing or replacing gas tank.

You could always replace it with a newer up-grade.

Bob

Both your links are for 66-78 applications, apparently. Would these be right for mid-late 80's 454's? I have read elsewhere that these people are very knowledgeable and produce an excellent rebuilt.

http://www.smicarburetor.com/product...8/productID/18

Phoenix · 10-21-2013, 01:47 AM

While there are lots of places that sell rebuilt carburetors, I have found that rebuilding your own existing carburetor eliminates a lot of headaches. GM used a lot of different carburetors on 454's over the decades that this engine has been in production, and switching carbs often causes additional problems from very slight incompatibilities. Just my opinion...

By the way, for those in or near Phoenix, that carburetor repair shop is:

Carburetor & Radiator Exchange (a.k.a., Short Money Carburetor Exchange)
9120 N. 7th Street, Phoenix, AZ 85020
Phone: (602) 944-0800

Note: I have no affiliation with this business, other than being a satisfied customer. Over the years, I had the carburetor on Hal, our old 1978 Chevy crewcab pickup with 454 V8, rebuilt there 3-4 times.

Protagonist · 10-21-2013, 05:40 AM

Quote:

Originally Posted by Jenniflow

The gas I'm using is about six months old…

The older the engine, the less happy it will be with ethanol-blend gasoline. Especially gas that sat for months so that phase separation could occur. Once you get it running the way you want, you would be well advised to run the engine every couple of weeks even when you're not going camping, preferably actual driving and not just idling since that will also agitate the fuel in the tank. But even if you just run it at idle, you'll make sure there's no stale fuel in the carburator bowl or fuel filter.

Quote:

I just remembered that I have about six bottles of that Shell Oil in one of the compartments. I bet it's over ten years old! (Long story). I'm also betting I can't use that any more, right? And I wouldn't want to add any of it in top of whatever's in there now? (I have to check with the garage that changed the oil in March.)

As long as the containers are still sealed there should be no problem using them. But shake them to a fare-thee-well before opening.

ROBERT CROSS · 10-21-2013, 05:47 AM

Quote:

Originally Posted by Punch

Both your links are for 66-78 applications, apparently. Would these be right for mid-late 80's 454's? I have read elsewhere that these people are very knowledgeable and produce an excellent rebuilt.

SMI Carburetor Marine/Towing/RV/Off-Road Rochester Quadrajet 750CFM Towing / RV / OffRoad Rochester Quadrajets Rochester 4BBL Quadrajet 750CFM SMI- Sean Murphy Induction

Reputation/experience is everything. The best advise....call and make sure they are clear on your application. You can be pretty sure that the Q-jet on the MH is different than the one on a Vette. The same goes for any replacement you may be considering.

I built a 350 for our Jimmy years ago, the Holley replacement was a worthwhile up-grade, especially during our Bflo Winters.

Bob

Jenniflow · 10-22-2013, 10:19 AM

These are all really helpful points, thanks. Getting a rebuild make sense to me, at least at first pass, so I'll look for an Experienced Mechanic because the way life is here, I'm unlikely to try to learn to do it myself.

There are lots of hot rodders around. Come to think of it, my cousin in Santa Cruz is a hot rodder. But I don't believe he still gets under the hood. I'll have to check.

Yesterday, I had to move the moho again so I gave it some gas, started the engine, and let it run for about 25 minutes before moving it. No problem. I may have reset the clutch by mistake on one of those other attempts when I didn't give it much gas before I started it and ended up pumping in more after it was running. Probably too much more. I have to remember that driving this thing is really different from driving my old M3. Usually I remember before I start the engine!

Also, I'll check to see what the garage put in the engine last time around and what I need to top it off with.

cwf · 10-29-2013, 09:02 PM

Results?

Jenniflow · 10-30-2013, 12:14 AM

Due to time pressures, I've had to delay the service on the coach until the spring. But I was able to move it without incident once I started it carefully and warmed it up well.

When I do get her looked at I will report! Thanks for asking!

Jenniflow · 04-11-2014, 10:52 AM

Ok, it's coming to the Great Moment when we remove the carburetor for rebuild. I have found someone who is a hot rodder of Dodge Rams who apparently knows these engines. I'm figuring having him remove it is a good choice? The chances of my finding someone in my neighborhood who knows the 345s is very slim. I could take it to the garage where they did the brake work, but that's where I got the chin-stroking treatment I mentioned earlier. No one there very familiar with AS mohos.

For lack of anything better to do, I'm thinking we'll send the carb to the guy at SMI who's in Southern CA. I've emailed him to ask if he's familiar with the unit and the application.

Jenniflow · 04-04-2015, 07:35 PM

Hi folks!
If it weren't for life, I'd have gotten a lot of stuff done by now!

So here's a new piece of advice on the rebuilt carb question. I was about to call SMI, and then I heard this and thought I'd run it by you-guys to see if you had any thoughts.

I've been trying to find a mechanic in the greater Portland OR area who could remove and replace a rebuilt carburetor and in the process of not-yet-finding-one, I ran into this piece of advice, by a self-named Geezer Mechanic:

"1. Find an old Geezer mechanic and it's wiser to buy a remanufactured carb instead. They will have new bushings and are better builds than a "bench job." They will have new floats, power valves, pull-offs and such. Just a better value in the long run.

2. I wouldn't waste time paying for the labor rebuild. Purchase a remanned one from most any auto parts store around portland. Make sure the mechanic checks floats and external linkage presets, install, adjust idle mixtures/auto choke, set trans kick down (app to auto trans) and be done with it. (Holley has online adjustment info. if it's a Q-jet, carter, FoMoCo/Autolite, have to get the manual or contact them and have them email set up procedures."

My questions are:
1) Do any of you think I can/should find a remanned one rather than a rebuilt one? And are they available for this rig? A 1986 345 MH?

2) Do any of you know a mechanic in Portland who could knowedgeably replace the old with the new, whatever it turns out to be?

thanks! And happy holidays!

Phoenix · 04-05-2015, 02:50 AM

Your best bet is to rebuild your existing carburetor. It will probably be about the same price as buying a remanufactured one, but you won't face the challenges of trying to get a slightly different carburetor with the same stock number on it to run on your engine.

I'd check out speed shops, auto parts stores that specialize in parts for vintage cars, and the local car shows that display old muscle cars. Someone there will know where to find a shop that will rebuild your old carburetor to like-new condition.