Engine dies: possibly found Heated Air Inlet (HAI) system problem...

[RickOregon]

Hello Older Generation Subaru Folks,

 

I think (hope) I've found the solution to a problem that has plagued our '86 carbed Subaru EA82 for the last couple years... every time the wagon goes through water (or slush) it wants to die. After waiting by the side of the road for awhile, one can start the beast and continue, but often it will take considerable fuel to make the few remaining miles to the destination..

 

After a recent occurrence, I decided to take drastic action. I got a spray bottle of water and started the car. Then I sprayed copious quantifies of water on separate sections of the engine hoping to find what would kill it. Let me tell you, I know the coil, distributor cap and spark plug wires on this Subaru could swim and *still* that engine would run!

 

Finally, using this technique, I discovered the air control valve in the air intake was not opening up to "fresh air" after the engine warmed. Instead, the air was being drawn (all the time) from the "air stove" around the exhaust pipe.

 

This warm air is only suppose to be used when the car is warming up, then a mixture of fresh and air-stove air is drawn in to keep the carb air in the range of about 100 F to 130 F. In my case the carb was sucking *only* air from the air stove. Problem with sucking only heated air from the muffler region is whenever the water spray from the road overwhelms the air stove (right at the bottom of the car), the carb sucks in a lot of water/steam, sometimes warm, sometimes not-so-warm. The result is poor performance, poor gas mileage, or engine stopping entirely.

 

So, I found a spare temperature sensor for the air box (the plastic part you see when you take the air filter out on the right/passenger side of the housing). Happen to have a complete intake/carb/air box in my barn... I installed the new sensor, and there appears to be flow from both the fresh air intake and the air stove near the exhaust pipe. I'm keeping my fingers crossed that this fix will solve the problems we've had for quite some time. (Note: I could have just disconnected the air intake hose to the air stove at the exhaust pipe, but I was concerned this would lead to carburetor icing. One of the benefits of having 100 F air coming into the carburetor is you don't have to worry about any ice buildup during cold humid intake conditions.)

 

Anyway, what do you think, folks? Will Kate make it to and from work tomorrow? It's snowing here, and there will be a lot of wet roadway conditions when she heads that way..

 

Glad to be back. Sincerely, Rick

[Partsman]

Sounds logical.

 

I think the only true test will be the acid test - drive it through slush and puddles and see if you've got a winner.

 

Maybe it won't thaw for a few weeks for you and you can put off the test! I'm originally from Unity, and I'm coming out to God's country (no one else would have it!) in a couple of weeks to see my folks and do some snowmobiling. I hear it's a 20 year best snowpack! :banana: Am sure glad I have a Sub for the trip - might even get into 4LO!

[RickOregon]

Thanks for the feedback, Partsman. Unity gets pretty cold, I understand.

 

Well, Kate is staying home sick today, so I guess I've got another day before she'll need to take the Subaru back out into the elements again.

 

I was wondering if anyone has ever blocked off the front intake areas of the "air stove"... There appear to be four areas where air flows through this device. Two in the front (upper and lower) and two in the back (upper and lower). It seems to me that the front intake allows water and/or snow to enter and vaporize before the air/steam mixture is drawn upwards into the air intake hose. If there's too much water or slush, it seems that this stove could be overcooled leading to a cool, rather than a warm, air mixture entering the carburetor. This would cause the temperature sensor to further increase the vacuum resulting in even more of the intake air being directed from the air stove, causing even more cool/wet air to be "vacuumed" up into the carburetor.

 

I'm thinking about hammering the front air stove intakes nearly closed to prevent this unstable air flow situation. Or maybe making a cone-shaped "diverter" that overlaps the air stove intakes in the front and forces any water/slush away from this air path.

 

Has anyone done something like that? Or maybe there's supposed to be some protective shield on this car, and it's been removed. Could that be a possibility? Your insights will be greatly appreciated.

 

Just curious. Thanks, Rick

[RickOregon]

I indicated earlier that the "air stove" baffle on our Subaru has four inlets. Upon closer inspection I see it only has two: one on the top front and one on the top rear. This baffle goes around the catalytic converter.

 

Sorry for the earlier error.

 

Has anyone else had similar problems with water getting "sucked" into the air box via either the normal fresh air inlet or the hot air inlet?

 

Thanks, Rick

[Partsman]

(bump)

 

Alaskans, any comments?

[torxxx]

I installed a rubber exhaust hose from a marine Gas engine powered Jet boat instead of that ****ty foil hose that is oem..

 

I still ice up every now and then when its -50F but I've never noticed anything from the steam or water vapor that was mentioned..

I do not know if the actuator works completely on mine.. I think mine sucks from the heater hose all the time cuz I opened the top of the airbox on my 86 and it ran so much better getting more air