Engine/Transmission (1994 - 1998) Check your vacuum system

[Johnstra]

Since I bought my truck last August I've worried off and on if I have a blowby problem. My truck has never left puddles of oil under it and it's never puked oil out of the dipstick tube or CCV, but it's always emitted a steady stream of vapor out the CCV (looked almost like steam coming from the spout of a kettle) and overnight it would regularly leave 2 or 3 drops of oil. Also, I've had a hard to cure oil leak between the gear housing and block. Now I know why.



Tonight I'll rest easy knowing for sure that I don't have a blowby problem at all. I finally got around to testing my vacuum system and found that it was pulling only 5" of vacuum (manual says it should pull 20"). Didn't take long to find that my main vacuum line from the pump had a good sized hole chafed in it. Patched that and my vacuum went to 20".



With the vacuum problem fixed, I climbed under the truck with it idling and checked the CCV. Now, instead of the stream I see only a very faint and very light wisp of vapor. I'll be very interested to see what happens to my oil leak and whether I continue to drip oil at night - I'll bet both go away.



So if you have any issues at all that look like blowby... check your vacuum lines.



-john

 

[Matthug]

Thanks for the words of wisdom

 

[StevenP]

John, I got the same problem! I took my rig for some work to be done and when I got it back I had a strong flow of vapor coming out and I also at the same time lost my A/C blowing through the ducts! Can you tell me where to find that main vacuum line so I can check mine out?

Steve

 

[DJWyckoff]

on my truck its under the injection pump main line looks like a heater hose mine is a 12v

 

[Johnstra]

Steven - Like DJ says, the vacuum pump bolts to the gear housing underneath the injection pump. I think your 2000 should be the same. You'll see a 1/2" hose fitting on top of the vacuum pump that adapts to the smaller hard vacuum line.



I'll be yours is just popped loose and not broken or chaffed. Look up near the firewall for a vacuum junction. You should have several lines feeding into/out of it. I'll bet you have something loose there.



-john

 

[McLaughlin]

In my 97 the vacuum pump is on the end of the steering shaft. The vacuum line runs from there to the firewall just right of the cylinder head into a T connector and then to other places from there.