Sputtering Chrysler 3.6 Air Cooled

[pvanv]

I bought my 3.6 air cooled new in the mid 70's. This is the West Bend unit, with water pump for the lower bearing. Has had regular maintenance. Occasionally seems to lean out. The tillotson carb is very clean and yet seems to have an issue. Can run it in the test tank for an hour no problem But on the water it may slow down and sputter after 20 mins. Half-choke or more makes it run OK, so I assume it is not getting enough gas. Tank is clean, fuel lines are new, carb seems great -- float is free, and new needle/seat this summer. Thoughts?

 

[sweezy722]

Re: Sputtering Chrysler 3.6 Air Cooled

Be careful. Lean running is dangerous. Is the vent cap open and working properly. Some of them get clogged with dirt dobbers and spiders. Check to see if your primer bulb gets soft or goes flat. Also it could be a fuel pump. My experience has been that they show problems on top end first. Ethanol gas makes my motor a little funny on top end - an occasional sputter.

 

[pvanv]

Re: Sputtering Chrysler 3.6 Air Cooled

I understand that lean running is dangerous. I'd rather not condemn my old, low-hours motor for a new 4-stroke if I can fix this. Tank is clear, vent is open. I always run K-100 MG fuel stabilizer, which is designed to help with preventing phase separation of E10 gas.

This is a gravity-feed system, so no primer bulb nor pump. I have blown out the lines and shutoff valve with compressed air, and even installed a glass filter in the line from the tank. The carb looks as good as new, has a new needle and seat, and the float is free, etc. I do have a spare "parts motor", so maybe I'll try the spare carb -- yet I don't see anything wrong with the original one.

 

[kandil]

Re: Sputtering Chrysler 3.6 Air Cooled

I am not familiar with this carb but does it have a welch plug? if yes you might want to remove and clean the idle tube and replace with a new one check your float drop level

 

[pecheux]

Re: Sputtering Chrysler 3.6 Air Cooled

Had one of these that sputtered after a short while of wot. It was overheating due to the fact that I was using outboard 2 cycle oil which is for water cooled OB's. This air cool OB requires lawn mower type oil, basicaly 2 cycle oil for air cool motors and it keeps it running at a much lower temp. Mine ran at 24:1 mix which is probably why it did not cook running on water cooled type oil. Just a thought.

 

[pvanv]

Re: Sputtering Chrysler 3.6 Air Cooled

Good thoughts all.

I'm running Amsoil synthetic for OB applications (I think it's called Sabre), per Amsoil's recommendations. The manual originally called for 16:1 during break-in, then 24:1 for running. This was before the advent of TCW-3 ratings. With the better oil, I'm mixing at about 40:1 (the equivalent of 20:1 using the old oils), and also running K-100-MG stabilizer.

Before anyone yells that it's not enough oil, let me explain that with this oil, you run HALF the oil, because it's better oil. So a 50:1 engine can run at 100:1 if using Amsoil.

The big problem here is that the problem is intermittent. I can tank test for hours, and all is well. But of course, it's not precisely the same as running conditions. Also the spark plug looks OK -- nice and tan -- not really white, as would be expected if running prolonged lean conditions.

I am still suspecting a carb problem, but will be darned if I can find anything wrong. Maybe trying the "spare" carb will tell me a lot. Of course, since the Buffalo winter is right around the corner, it may be a while before I have a definitive answer.

Amazing that such a small, simple motor can be so difficult to diagnose.

 

[pecheux]

Re: Sputtering Chrysler 3.6 Air Cooled

I know the Amsoil Saber outboard oil ... used it last summer. BUT this oil is still made for water cooled motors that run on the cold side in oposition to air cooled that run hot.
Althought it does not seem to have anything to do with your current problem I personaly would use 2 cycle oil made for air cooled motors. Ex: Saber professional or any 2 cycle lawn mower or trimmer oil. But it's your OB not mine ...

Amsoil do make an air-cooled Saber 2 cycle oil so I am suprised they would have recommende the Saber Outboard oil for your air-cooled OB.

Cheers.

 

[pvanv]

Re: Sputtering Chrysler 3.6 Air Cooled

No question that the Chrysler West Bend motor does run hotter than a water-cooled powerhead. I asked the same question of Amsoil, since I use Sabre Pro in weed whackers, etc. They maintained that the Sabre would be fine, and said that a 50:1 ratio in the 24:1 air-cooled OB would be OK.

To be conservative, I run at 40:1, which should be the equivalent of 20:1. So far, I'm not noticing any undue ring wear due to thinning of the oil -- compression is great, but then this motor doesn't scream along at over 10,000 RPM, as do the small weed whackers, etc.

Of course, since the bottom bearing is technically water cooled, it could be that their recommendation takes this into consideration -- that the crankcase of this motor is colder than if it were only air cooled...

 

[steelespike]

Re: Sputtering Chrysler 3.6 Air Cooled

My experience with 6 different after market manuals dating from 55-89
also info on my Citgo TCW3 rated outboard oil Every air cooled outboard listed in time frame of available outboard oils reccomend OUT board oil.
Citgo TCW3 oil Quote"2 stroke engines including outboards,snowmobiles,motorcycles,chainsaws,string trimmers and lawn mowers"Also"exceeds requirements for TCW and TCWII"
No question that certain high performance 2 strokes may require
other oils.
Westbend and Chrysler quote "A cooling tube is located in the lower unit,which picks up water from below the anti-cavitation plate"(sic)"This water is directed to the exhaust portion of the lower housing and associated parts".Maybe it cools the bearing or more likely cools the exhaust so it doesn't over heat the bearing.

 

[pvanv]

Re: Sputtering Chrysler 3.6 Air Cooled

It seems that any modern 2-stroke oil (TCW-3) is a lot better than what we had in the 1970's, and that the synthetics are the best of them all. The water pump is pumping, though I could definitely use a new (hard to find) impeller.

So I don't feel that improper lubrication or overheating is causing the sputtering. I'm still thinking it's a problem in the carb -- emulsion tube or something like that.

 

[steve66]

Re: Sputtering Chrysler 3.6 Air Cooled

Hi I also have one of these motors with exactly the same problems.It starts perfectly nedds a bit of choke for a couple of minutes until warmed up then rund perfectly for approximately 20 minutes on WOT ,then it starts to slow and dies.Its not siezing as once stopped it still turens free.The fuel tank has been lined with redkote so no rust can get to the carb, a new fuel line and inline filter has ben added,carb is spotless and all jets are clear and the bowl is still full of fuel.Points have been cleaned and re gapped.I will try using different oil. I was wondering if you guys found any more solutions to the problem?
Many Thanks Steve

 

[Frank Acampora]

Re: Sputtering Chrysler 3.6 Air Cooled

Your engine is talking and you are not listening!

No matter what you think, it is overheating and slowing. Half choke runs cooler because it is richer and the engine will continue to run. So: try richening the mixture a bit.

With the 3.6, it is not a question of oil on the rings. 100-1 would probably be enough for that. That engine is a plain bearing engine and has no rollers on the con-rod (or the crank). Therefore, no matter what Amsoil says, or how good you think it is, you need a 24 to 1 mix. Some things are a given, and no matter how much you want them different, you can't have it.

NOW: Have you removed the shroud and cleaned the fan and engine fins to ensure enough airflow over them? Is the shroud complete or broken or bent? Low airflow, less cooling, --overheat. And yes, these little engines will run hot, but not be happy about it.

The water pump puts water into the exhaust and out the leg in the small holes below the reverse lock. The purpose of this water is to cool the exhaust so you don't burn yourself on the leg, and also keeps the paint from burning off the leg, making the engine look old, cheap, and junky (which in reality, it is.) Sorry! I'm a Chrysler fan but it is what it is.

 

[pvanv]

Re: Sputtering Chrysler 3.6 Air Cooled

Frank,

As soon as the weather breaks, I'll see about going richer on the oil. As for the airflow system, there isn't any internal shrouding; just the plastic outer cowling, and of course the underside of the fuel tank. Yes, it's all clear and clean.

Steve, one thing I noticed in your post, and that is that we have both added inline fuel filters -- which these motors did not have from the factory. I know it sounds unlikely, but is there a possibility, with such low gravity-fed fuel pressure, that the filter causes some restriction to fuel flow, possibly lowering the fuel level in the carb? The tank is less than a half-inch above the carb, so fuel pressure is minimal. Of course these motors don't burn a lot of fuel.

Reason I ask is that I recently went through a kawasaki-powered toro snow pup (paddle-type snow blower), and added an inline filter. Ever since then, it suffers from what seems to be a similar fuel starvation, when at or below a half tank of fuel. Might be a related kind of problem.

 

[steve66]

Re: Sputtering Chrysler 3.6 Air Cooled

Hi Frank,The fuel filter is a very plausible solution,the little motor is now running again.It was one or a mixture of 3 things.As you said with the fuel filter i filled the tank full also i replaced the plug with a cooler variety and last but not least i replaced the coil as i thought it may be failing as it got hot.Just need to get a real annoying identical problem on 4 identical 4hp suzuki motors.
Thanks everybody for there help.
Steve

 

[pvanv]

Re: Sputtering Chrysler 3.6 Air Cooled

Hi Frank,The fuel filter is a very plausible solution,the little motor is now running again.It was one or a mixture of 3 things.As you said with the fuel filter i filled the tank full also i replaced the plug with a cooler variety and last but not least i replaced the coil as i thought it may be failing as it got hot.Just need to get a real annoying identical problem on 4 identical 4hp suzuki motors.
Thanks everybody for there help.
Steve

So Steve,

Are you saying that everything is A-OK now? Are you still running an inline fuel filter? If so, maybe it was indeed a coil issue, and maybe that's something for me to look at. Is the colder plug still coming up the proper color after running at WOT for a while? What plug are you running?

Thanks,

Paul

 

[steve66]

Re: Sputtering Chrysler 3.6 Air Cooled

Hi Paul,Yes everything seems to be fine now,yes still running the fuel filter but am planning to take it out and give it a good run this weekend.I was using a NGK B5HS,but to be honest i was experimenting with different cooler plugs i cant remember which one is in at the moment.I will check it for you later.Incidentally the coil is a bog standard lawn mower coil,mine was a tecumseh,very cheaply priced too.
Regards Steve

 

[pvanv]

Re: Sputtering Chrysler 3.6 Air Cooled

Seems the NGK B5HS would be a bit on the hot side. The Champ H8J should cross to NGK B6L

Incidentally, Franz Marine had Factory coil, points, condenser, and impeller, all at reasonable prices.

 

[pvanv]

Update: Sputtering Chrysler 3.6 Air Cooled

Update: Sputtering Chrysler 3.6 Air Cooled

So I still have the "running out of gas" symptom.

After a fair amount of investigation, and swap-out of inexpensive bits, I haven't quite nailed it down... yet.

I have installed new points, condenser, coil -- hopefully ruling out any ignition-related thermal issues. Also trimmed ends on plug wire, and swapped-in a different Tillotson CO carb. The carb is very clean, and the float is adjusted correctly. In addition, for test purposes, I bypassed the fuel filter and gas shutoff valve, as it did appear that fuel was being restricted somehow by the inline filter and/or valve. The tank is definitely as clean as a whistle, and the vent definitely is clear and open. Running 24-to-1 TCW-3 oil. Fins on flywheel are clean, and everything looks nearly new. Fuel hose is new.

In the test tank, the motor starts from cold with a few pulls... normal so far. requires a bit of choke for a couple of minutes... normal so far. Then, after running for about 15 mins, the motor will slow and stop. During the slowdown, adding choke keeps it running briefly, but it still seems to run out of fuel.

Motor is not seized -- pulls normally, but will not immediately restart. Wait 1 minute (maybe allowing a trickle of fuel into the carb?), and it will restart, but now will slow and stop after maybe 2 minutes of running. Can repeat this cycle forever.

So... it seems to be thermally aggravated, and it definitely seems to be low fuel in the carb bowl. The needle and seat look perfect. I tried running with the fuel cap ajar, thinking maybe a restriction in the vent might cause this. Nope. Again, adding some choke helps prolong the slow running, but it will still stall after a few more seconds. Also, when using the original fuel shutoff valve setup, I found that "pumping" the shutoff valve piston while the motor was slowing down (pushing a few more drops of fuel to the carb) seemed to help prolong the run time.

Really has me scratching my head -- so simple a setup, yet the solution evades me. There has got to be something that I have overlooked.

Ideas?

 

[pvanv]

Re: Sputtering Chrysler 3.6 Air Cooled

I have now verified that adding a primer bulb, bypassing the fuel shutoff valve, allows me to force fuel through to the carb, and I can keep it running. Of course, if I allow it to run without pumping, it will slow and stop. But why? The tank is clean as a whistle, the carb has been swapped out, and yet it seems to "run out of gas". But while it's slowing down, I can pump about a half a bulb (about a carb bowl's worth), and it perks back up.

So it would seem that even with a "good" (new) needle/seat, and proper float height, I am not getting enough gravity-feed fuel.

Thoughts?

 

[pvanv]

Re: Sputtering Chrysler 3.6 Air Cooled

I have now verified that adding a primer bulb, bypassing the fuel shutoff valve, allows me to force fuel through to the carb, and I can keep it running. Of course, if I allow it to run without pumping, it will slow and stop. But why? The tank is clean as a whistle, the carb has been swapped out, and yet it seems to "run out of gas". But while it's slowing down, I can pump about a half a bulb (about a carb bowl's worth), and it perks back up.

So it would seem that even with a "good" (new) needle/seat, and proper float height, I am not getting enough gravity-feed fuel.

Thoughts?

I just revisited this issue... Definitely good ignition, new OEM needle/seat, carb is super-clean and float height is level when inverted, perfect-looking gas tank. No restrictions or junk in the vent or fuel elbow. Installed new gas lines and deleted fuel filter, so it is as it was from the factory.

The carb definitely runs out of gas at times, particularly when warm, so maybe the rubber in the seat is swelling a little with heat? I tried adding more tilt to the motor (to increase gravity fuel pressure) and removed the gas cap, which seemed to help some, but it still stalls (without seizing). Verified that adding a primer bulb and squeezing it overcomes the problem. So it needs more fuel pressure for whatever reason. Maybe it's possible to increase float drop for more robust fuel delivery? The needle does not have very much travel from fully open to closed.

QUESTION:

There once was a fuel pump kit for these, so you could connect an external tank. That might solve the problem. I have not been able to locate a kit, though. Apparently they were very rare even when new. (Franz does not have one). Does anyone know whether the pump kit attached to the crankcase or whether it was a different carb (with integral pump)? If I could retrofit a pump, even if from a different make/model/size motor, I am certain that it would work properly.

Any ideas? Thanx.