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Help on tracing an exhaust leak
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Author:  sixaddict [ Fri Jan 02, 2009 3:42 pm ]
Post subject:  Help on tracing an exhaust leak
Searched but didn't find a thread on this...

I need to figure out where the exhaust fumes are coming from. Basic visual doesn't show any holes. What next, what order, what to look for?

Car is a 69 Dart, 225, stock type full exhaust to downturned tailpipe by back bumper, decent door seals, one bad area of the trunk lid seal. No holes in floors.

Appreciate your advice - to just look randomly could be EXHAUSTING! AHAHAHAHA!!!!! (Sorry.)

Thanks in advance!
~Scott
Author:  Aggressive Ted [ Fri Jan 02, 2009 3:47 pm ]
Post subject: 
When do you smell it? While sitting at a light? or under way....?

Are you smelling blow by or exhaust? Blow by can come between the hood and into the air intake for the heater.

How many miles on the engine? Does it use any oil? Could there be any blow by sneaking in? Is the engine super clean?
Author:  SlantSixDan [ Fri Jan 02, 2009 4:02 pm ]
Post subject: 
Can you round up a helper? Rig up a pile of wood or something so that you can cram a pile of rags against the end of the tailpipe to restrict the exhaust, and have your helper trickle oil down the carburetor with the engine running at a fast idle. This will create exhaust smoke, and you can look for where it's escaping under the hood or under the car.

Ted's idea about blowby is a good one — if the engine is old and whipped, and/or the PCV system isn't working correctly, and/or the hood-to-cowl seal is crispy or missing, the interior of the car will start to reek of crankcase fumes.
Author:  sixaddict [ Fri Jan 02, 2009 4:53 pm ]
Post subject: 
Engine is old - that's all I know. I've had it for 6 mos.; It's been passed around like a drunken cheerleader and there's no trail of receipts. I doubt it's the original engine or hasn't been rebuilt at some point if it is... Don't know where to find the numbers on the block to check that. But it's strong and uses very little oil.

Top end was redone, reman head, maybe 2 years ago. Very clean for a 40 yr. old driver. Now PVC, I haven't checked that... I'll do that first.

I smell it while moving.

Hood to cowl sealing etc. I'll check that.

Dan - great idea, will do that once it's got a good carb on it! :D

Thanks! ~Scott
Author:  wjajr [ Fri Jan 02, 2009 6:24 pm ]
Post subject: 
A bad trunk weather strip will let exhaust fumes into the car when it is driven.
Author:  sixaddict [ Fri Jan 02, 2009 6:49 pm ]
Post subject: 
Another good clue... and you know, the cabin isn't sealed off from the trunk like it should be. Speaker holes in the shelf, etc. It'll be good to know where it's leaking, but nice to know where it's coming in too. My guess is its a combo platter of any of the above.

Thanks! ~Scott
Author:  wjajr [ Sat Jan 03, 2009 10:17 am ]
Post subject: 
Quote:
Another good clue... and you know, the cabin isn't sealed off from the trunk like it should be. Speaker holes in the shelf, etc. It'll be good to know where it's leaking, but nice to know where it's coming in too

The trunk is never hermetically sealed from the passenger compartment. One would not need to have a leaking exhaust system to have fumes enter via a bad trunk weather strip.

My trunk leaks fumes due to misalignment of the rim that the weather seal seats on caused by previous owner getting taped in the rear end. I thought I had repaired the misalignment, but...not quite. I never really noticed the problem because the top is down 95% of the time until a little cold weather carburetor testing took place last month.

Just close your self into the trunk in bright sun light, and look for light around the seal.

Improtent tip:

Be sure to leave the trunk key in the trunk lock, and take a pair of pliers into the trunk with you to turn the lock's tail piece so you can get out, or find a friend to help.
Author:  Reed [ Sat Jan 03, 2009 12:08 pm ]
Post subject: 
Yeah, leaving your friend locked in a trunk that has an exhaust fume leak is never a good idea... :wink:
Author:  65Dodge100 [ Sun Jan 04, 2009 7:37 am ]
Post subject: 
Quote:
Just close your self into the trunk in bright sun light, and look for light around the seal.
You can also dust around the lip with baby powder, close the lid, open it and see where the gasket touched.

Danny
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