Intermittant hesitation problem on acceleration when hot

[Guest]

I have a '91 240 wagon which I have been slowly restoring. It had been
well cared for up until about a year ago, and then totally neglected.
I've repaired a crumpled fender, rear deck replacement, rewiring the
rear deck, and miscellaneous wiring gremlins.

The car always starts up. It idles smoothly. It gets decent gas milage
(19 mpg city driving, that's about right, isn't it?)

I loaded it up and took it on an 800 mile trip. I know it needs a new
clutch fan, because it overheats when sitting in traffic. I also have
a new radiator ready to put in. But...

Occasionally when driving around 65 mph on the highway, the car would
hesitate, lose power. It really wouldn't slow down as much as just not
go faster. It never stalled, but it seemed like it might once or
twice. It might have idled a little rough when that problem was
happening, but not much.

Occasionally, but rarely, it will hesitate on a hot day after driving
only around 10 miles.

I looked around and checked small hoses under the hood... they seem
fine..

Any suggetions would be appreciated.

Thanks in advance,
Larry

 

[Randy G.]

Check for proper opration of the hot air thermostat in the air
cleaner. Try removing the hose that goes from the ehxaust manifold to
the air cleaner (or just disconnect it at the cleaner.

Could be fuel starvation (weak tank pump or accumulator problem). Does
it do it more often when the tank is low?

I have a '91 240 wagon which I have been slowly restoring. It had been
well cared for up until about a year ago, and then totally neglected.
I've repaired a crumpled fender, rear deck replacement, rewiring the
rear deck, and miscellaneous wiring gremlins.

The car always starts up. It idles smoothly. It gets decent gas milage
(19 mpg city driving, that's about right, isn't it?)

I loaded it up and took it on an 800 mile trip. I know it needs a new
clutch fan, because it overheats when sitting in traffic. I also have
a new radiator ready to put in. But...

Occasionally when driving around 65 mph on the highway, the car would
hesitate, lose power. It really wouldn't slow down as much as just not
go faster. It never stalled, but it seemed like it might once or
twice. It might have idled a little rough when that problem was
happening, but not much.

Occasionally, but rarely, it will hesitate on a hot day after driving
only around 10 miles.

I looked around and checked small hoses under the hood... they seem
fine..

Any suggetions would be appreciated.

Thanks in advance,
Larry

__ __
Randy & \ \/ /alerie's
\__/olvos
'90 245 Estate - '93 965 Estate
"Shelby" & "Kate"

 

[Guest]

I've checked the fuel level, it doesn't appear to have anything to do
with how much fuel I have.
Regarding the hose that goes from the exhaust manifold to the air
cleaner,.. what should happen when I disconnect it, you think I might
be able to reproduce the problem?

Thanks in advance,
Larry

 

[Randy G.]

The large, round, aluminized, corrugated, cardboard-y hose is the one
I was referring to. it allows the air cleaner to draw hot air into the
intake system when the car is cold to speed warm-up time and lower
pollution at the exhaust pipe. Inside the air cleaner is a flap
controlled by a thermostat. WHen the air temp is low it opens the flap
so that the car draws air from the hot air tube thing. Once it warms
up it is supposed to close, only allowing cold air through. If the
thermostat fails or the flap doesn't work it can alow only very hot
air through the intake system. By temporarily removing the hot air
duct tube at the air cleaner, no matter wht, the air cleaner will only
draw cold air. I recommend getting the Bentley Volvo 240 service
manual. It is money well spent, and they show how to test the
thermostat, among lots of other useful info.

I've checked the fuel level, it doesn't appear to have anything to do
with how much fuel I have.
Regarding the hose that goes from the exhaust manifold to the air
cleaner,.. what should happen when I disconnect it, you think I might
be able to reproduce the problem?

Thanks in advance,
Larry

__ __
Randy & \ \/ /alerie's
\__/olvos
'90 245 Estate - '93 965 Estate
"Shelby" & "Kate"