1986 240 DL - intermittent lack of power coupled with overheatedexhaust manifold

[David (archive)]

My 86 240 DL nearly left me walking home from work. Had 2 episodes:

The first time, the car seemed low on power. Could only go about 65 mph. Got home and popped the hood, in the dark of night the #3 & #4 exhaust manifold pipes were glowing red. Felt like it was running on 3 cylinders, checked plug wires and one shocked me, so I replaced them. Everything seemed fine during testing and the next day. Thought I was done...

The next afternoon, however, the problem returned as soon as I hit the highway. I could only run about 45 on flat ground. Manifold was hot again. Tried slowly increasing the engine speed while in park, runs fine up to between 2000 and 3000 rpm, but after that the engine would just sputter.

Parked it a few days, just drove it around town tonight, no problems at all. I hate intermittent problems...

My thoughts, please throw in your $0.02:

1. Clogged fuel filter (did check the fuel pressure regulator, it is working but I don't have a gauge to measure the actual pressure). I may just replace this over the weekend anyway, it is after all a regular maintenence item (got the car used, don't know when it was changed last)

2. Clogged exhaust, as in the catalytic converter.

3. Bad air mass meter.

Thanks for the input - David

 

[Joseph Oberlander]

My 86 240 DL nearly left me walking home from work. Had 2 episodes:

The first time, the car seemed low on power. Could only go about 65 mph. Got home and popped the hood, in the dark of night the #3 & #4 exhaust manifold pipes were glowing red. Felt like it was running on 3 cylinders, checked plug wires and one shocked me, so I replaced them. Everything seemed fine during testing and the next day. Thought I was done...

Sounds like a worn cam or something electrical. You are basically missing two cylinders and the others are running hard to compensate, probably quite a bit higher rpms.

 

[Anthony Flint]

I remember reading somewhere that could also be caused by timing being severely retarded; it applied to turbo-equipped models, but I'm assuming that it could also be applied to non-turbo models.

Tony

 

[volvowrench]

My 86 240 DL nearly left me walking home from work. Had 2 episodes:

The first time, the car seemed low on power. Could only go about 65 mph. Got home and popped the hood, in the dark of night the #3 & #4 exhaust manifold pipes were glowing red. Felt like it was running on 3 cylinders, checked plug wires and one shocked me, so I replaced them. Everything seemed fine during testing and the next day. Thought I was done...

The next afternoon, however, the problem returned as soon as I hit the highway. I could only run about 45 on flat ground. Manifold was hot again. Tried slowly increasing the engine speed while in park, runs fine up to between 2000 and 3000 rpm, but after that the engine would just sputter.

Parked it a few days, just drove it around town tonight, no problems at all. I hate intermittent problems...

My thoughts, please throw in your $0.02:

1. Clogged fuel filter (did check the fuel pressure regulator, it is working but I don't have a gauge to measure the actual pressure). I may just replace this over the weekend anyway, it is after all a regular maintenence item (got the car used, don't know when it was changed last)

2. Clogged exhaust, as in the catalytic converter.

3. Bad air mass meter.

Thanks for the input - David

There are two problems:

1. The engine is running rich for some reason--bad injector or pushing oil into the exhaust.

2. Because of 1. the cat is restricted and overheating, hence the build up of heat in the exhaust runners.

Bob

 

[David (archive)]

There are two problems:

1. The engine is running rich for some reason--bad injector or pushing oil into the exhaust.

2. Because of 1. the cat is restricted and overheating, hence the build up of heat in the exhaust runners.

Bob

Thanks for the advice. It *might* be running rich, will check the plugs & tailpipe for evidence. The engine has never used a drop of oil (hardly even gets it dirty). I'm gonna drive it locally this weekend to try to catch it in the act. But so far it ONLY fails when I'm making the 40 mile trek home after a long day of work ;-)

 

[Mike F]

Thanks for the advice. It *might* be running rich, will check the plugs & tailpipe for evidence. The engine has never used a drop of oil (hardly even gets it dirty). I'm gonna drive it locally this weekend to try to catch it in the act. But so far it ONLY fails when I'm making the 40 mile trek home after a long day of work ;-)

I'd also try a new set of plugs in case they're breaking down, as well as the cap and rotor.