I have a Volvo 745 of 1991 years model. It has a B230F engine and is a manual. On wet rainy days my car will crank but wont start. If I connect my engine block heater and cab heater for a hour or two, then my car will start in a second with no problem whatsoever once it gets going. It will run fine and there is no other problem whatsover. If its freezing temp the car will start without problems. Its only on rainy, wet days. I checked the sparkplugs with a water spray bottle on a dark night and I saw no sparks or anything. So I think the cables are OK. You think my cap and rotor are bad? But then how and what does the engine block heater and cab heater do to solve the start problem so that the car then can start? I am puzzeled.

 

Use the spray bottle on the dist cap & rotor on a dry day when the engine is cold. I had a similar problem on my '91 240 and when I took the spray bottle on the dist cap, it failed to start.

 

Yes, you could be right. But what I dont understand is how the blockheater and cab heater solves the problem. If the car wont start I connect them and an hour later it starts straight away. There is no heat coming up towards the dist cap and rotor from the cab heater so its still "damp/wet". So whats the magic?

 

our 87 240 has developed a water leak around the windshield, which is getting the whole inside of the car damp with dew after a rainstorm, when its like this, its very hard to start and runs very poorly til it drys out...

sadly, we're probably going to scrap this car. the body is in great shape, it runs well when its not wet, but in addition to the water leak, it needs shocks, front suspension control arm bushings, and brakes... and the tranny is getting tired and starting to slip a bit, so the cost of restoring all that exceeds the value of a 500,000 miler we've had for 27 years.

 

Ok, next time it rains I will open the hood and look if there is any water/moisture around the firewall. The cap and rotor are there at the back of the engine towards the firewall. So again you too could be right. But Pierce, how does the blockheater and cab heater solve the problem? Once it starts it runs like perfectly new. I am puzzeled.

 

heat dries stuff out.

 

You mean the heat from the block heater that heats up the coolant in the engine? You mean that coolant thats gets warm/hot takes away the moisture from the cap and rotor from inside although it gets only 104 degrees Farenheit/40 degrees Celsius warm in the coolant? Or you mean the cab heater that does the job?

 

Have you determined that it is the dist cap & rotor? Its been a long time since I used a block heater so I don't know how warm it will get the head but if it is warm enough it could affect the distributer.

I would use the spray bottle on a dry day when it is dry and spray down different areas of the engine till the problem can be pinpointed.

 

our 240, the wet electric problem is under the dash, I'm pretty sure. when my daughter got the car home after a year up in the northwet (Humboldt coast), the inside is so damp that on a cold day, anything metal inside is coated in dew. After a few dry days here, I got it started, and ran the heater full blast with the fan on high, and the back windows open an inch or two to drive out the moisture.

 

I finally found out what the problem was. One day when it was raining I put only the engine block heater on. 2 hours later when I tried to start it I could not succeed. Next day I only put the cab heater on and left the engine block heater off/out. To my surprise, 90 minutes later the car started without any problems. Now I came to know that water must be leaking into the hood somehow. On opening the hood I saw that the rubber seal was bad so I helped seal it better with some black underbody compound I had home. Then I checked the rubber seal just below the windshield and saw a crack there as I have some rust around there. When I pressed that with my finger I could see the crack widening and water could have easily entered there. I sealed that with the same compound. Some days later when it rained again I went to start my car and it started easily like it always has done. Finally I have solved my problem. Now my car runs perfect like it always has done. Thanks, all you guys for your help.