The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - 47-55.1 Eliminate draft tube options

**TX3100Guy** · 12-16-2023, 12:45 PM

ok, here is the full story. A year ago I did see the article on Deve's website and bought his kit with a grommet, PCV, and stainless steel tubing over to my intake manifold. It enters the manifold at a tee fitting. The other side of the Tee fitting is a vacuum/boost sensor since I need to monitor that for the supercharger. Another sensor is affixed to the fuel pressure regulator to ensure that fuel pressure increases as normal vacuum at idle increases to boost pressure when the supercharger engages in higher rpm modes.

As I started test driving the truck, I was looking for any leaks given all the work done to the engine, transmission, brakes, and quick change differential. I noticed a drop here or there, which I would address but nothing major. Idling in the garage and/or the driveway produced no oil spotting (which make my wife happy) until I parked it overnight, then I noticed not a drip, but a puddle under the front of the engine.

I'll spare you all the details of where and how I looked for the source of the leak, but I traced it to coming from behind the crank pulley. Given all the customization that's been done under the hood of this truck, that entailed removing the drivers side outer and inner fenders, the alternator and AC compressor, to get the radiator out so that I could get to the crank pulley/balancer. Luckily I hadn't yet installed the grille.

The oil wasn't coming from the seal around the crank as I had surmised, instead it was coming from the bottom of the timing cover. Turns out, one of the bolts holding the bottom of the cover was stripped and the oil was coming out of the bolt hole. In the end, I used a tap to enlarge the hole one bolt size (fine thread) and eventually taped both of the holes of the timing cover and block. They are now held securely with Grade 8 - 7/16 bolts instead of the 3/8 that were there.

I told this story to a good friend about the oil leak and before I could finish my thought, he asked me "did you try to rig up a PCV instead of the road draft tube". When I answered yes, he told me a story about doing something similar to an old Merc engine and that the amount of blowby coming out of the draft tube opening created a problem with some of the seals on his engine creating an oil leak.

This is what got me thinking about setting up an alternative arrangement to the one I installed from Deve.

12-16-2023, 12:45 PM	#6
TX3100Guy Senior Member Join Date: Mar 2022 Location: Lucas, TX Posts: 459	Re: Eliminate draft tube options ok, here is the full story. A year ago I did see the article on Deve's website and bought his kit with a grommet, PCV, and stainless steel tubing over to my intake manifold. It enters the manifold at a tee fitting. The other side of the Tee fitting is a vacuum/boost sensor since I need to monitor that for the supercharger. Another sensor is affixed to the fuel pressure regulator to ensure that fuel pressure increases as normal vacuum at idle increases to boost pressure when the supercharger engages in higher rpm modes. As I started test driving the truck, I was looking for any leaks given all the work done to the engine, transmission, brakes, and quick change differential. I noticed a drop here or there, which I would address but nothing major. Idling in the garage and/or the driveway produced no oil spotting (which make my wife happy) until I parked it overnight, then I noticed not a drip, but a puddle under the front of the engine. I'll spare you all the details of where and how I looked for the source of the leak, but I traced it to coming from behind the crank pulley. Given all the customization that's been done under the hood of this truck, that entailed removing the drivers side outer and inner fenders, the alternator and AC compressor, to get the radiator out so that I could get to the crank pulley/balancer. Luckily I hadn't yet installed the grille. The oil wasn't coming from the seal around the crank as I had surmised, instead it was coming from the bottom of the timing cover. Turns out, one of the bolts holding the bottom of the cover was stripped and the oil was coming out of the bolt hole. In the end, I used a tap to enlarge the hole one bolt size (fine thread) and eventually taped both of the holes of the timing cover and block. They are now held securely with Grade 8 - 7/16 bolts instead of the 3/8 that were there. I told this story to a good friend about the oil leak and before I could finish my thought, he asked me "did you try to rig up a PCV instead of the road draft tube". When I answered yes, he told me a story about doing something similar to an old Merc engine and that the amount of blowby coming out of the draft tube opening created a problem with some of the seals on his engine creating an oil leak. This is what got me thinking about setting up an alternative arrangement to the one I installed from Deve. __________________ 1953 Chevy 3100 - 5 window 1/2 ton pickup My 1953 Chevy Work-In-Process Photo Gallery "I don't have a carbon footprint, I drive everywhere."