Blow By

[KWahl]

I've got a GMC 2500 with almost 400,00 miles on it and now getting some blow by. Any suggestions on resolving it? I've seen some posts that says using fuel and oil additives would help reduce the blow by. It's not bad but I don't want to leave it and it get worse, especially if there is something that I can do. I do plan on upgrading soon, just not now.

 

[Twisted Steel Performance]

Frankly there is nothing you can pour in it that will fix it. At 400k miles it's tired and well worn, rings and cylinders are wore out. Simple fact is either plan a full rebuild or trade it on something else. For your info a true 100% plus build will or should be in the 8k range and up.

 

[Will L.]

There is a product called “engine restore” that when tested shows slight improvement but won’t solve it.

For the blow by loosing oil- get rid of the cdr, install a provent200 in its place. (They make many sizes, the 200 is correct for us)
It is the most effective “catch can” available. You can buy the ebay knock off to save money, but throw away the ebay filter inside and buy the real provent filter. The only bay filter doesn’t work well, but the provent filter fits in the knock off housing.

You could modify the oil pan and make it an auto return but for this engine that is nearing death- I wouldn’t. Just check the can once a week and after a while you will learn when it’s full. Just drain it into a bottle and pour it back in the engine.

Amazon.com

Here is how to drain it to pour the oil back in. I suggest adding a thread on cap to the ball valve to keep it clean so you can reuse the oil.

 

[KWahl]

Thanks for the input, I guess I just wanted confirmation on what I already feared. It’s been a good truck and is still dependable and I’m just struggling on letting loose of the $$ to replace it.

 

[MrMarty51]

Thanks for the input, I guess I just wanted confirmation on what I already feared. It’s been a good truck and is still dependable and I’m just struggling on letting loose of the $$ to replace it.

At 400,000 miles a dealership would give nothing for a trade in on it. They might tell You blah blah boablahblah about how much they are giving You but in reality it is $000,000.01
Drive the old beast, pour in a bottle or two of that additive and use some Stanadyne fuel supplement and just drive it.
I do want to get that provent 200 for My truck and it has literally no blow by.
I would also like to dismantle the enjun and add a set of those gapless rings but that too all takes a lot of money and thats something I dont have.

 

[Big T]

Where do you mount the Provent 200 on our 6.5s?

 

[Will L.]

Where do you mount the Provent 200 on our 6.5s?

One example:

My Suburban Renewal Project

Just so I know what you are talking about, the provent just filters the oil out of the blow by and you got rid of the CDR Valve? What advantage does this give besides cleaner turbo and intake?

www.thetruckstop.us

 

[Big T]

One example:

My Suburban Renewal Project

Just so I know what you are talking about, the provent just filters the oil out of the blow by and you got rid of the CDR Valve? What advantage does this give besides cleaner turbo and intake?

www.thetruckstop.us

If it replaces the CDR, why mount it on the other side of the engine?

 

[Will L.]

Just where he chose to.

You can either make it auto drain or just have it hold the oil (usually a long hose down with a cap) and pour it back in yourself as needed. So placement depends on how you want to address that.
Then to promote less oil even making it into the can, the farther away the can is from the valve cover, the better- so long as you dont create a “p trap” and you have good airflow in your hose system.

 

[Will L.]

Hummer layout is different than a trucks. Centermount turbo, Much tighter area, etc.
But so near radiator on the passenger side because air filter is still on passenger side so running the hose is easy.

You want the highest ‘vacuum’ into the can possible. In racing an actual vacuum generating pump is used, so the hose from intake tube to can should be short. But you are playing engineer so imo make things adjustable when starting out. Once you learn what the best option is- then get rid of the bailing wire holding it and build a bracket

You don’t want it next to the turbo. Heat and plastic not going together with flammable liquid inside is probably a bad combo. Haha.

And DO NOT use the auto drain tied in with the turbo drain. You don’t want the turbo oil drain flow competing for free flow. I suppose someone could fabricate a new cover plate that has two separate tubes that wont interfere with each other somehow- but that sounds like more work to me than an oil pan bushing install.

 

[Big T]

Just where he chose to.

You can either make it auto drain or just have it hold the oil (usually a long hose down with a cap) and pour it back in yourself as needed. So placement depends on how you want to address that.
Then to promote less oil even making it into the can, the farther away the can is from the valve cover, the better- so long as you dont create a “p trap” and you have good airflow in your hose system.

Looks like he's tapped the Oil Fill and is not using the CDR hole on the valve cover???

 

[Will L.]

Yea, some of the older oil fill had the vent pull from there. There is an oil splash shield in the timing cover. So by using 2 valve covers that dont have holes, and pulling the vent from the oil fill- he gets a more equal “vacuum” on the two sides of the engine.

All the oil condenses under both valve covers the same and pours down. The excess pressure- which is all you really want to get rid of, gets removed from the crank case in a location away from flying oil.

The entire idea is trap oil in the crankcase wether liquid or gaseous (mist). But the pressure has to come out of the crankcase. The pressure is created primarily from blowby of the rings. Then the movement of the pistons will generate some airflow and a tiny amount of pressure.

High performance engines actually use an external pump to suck the crankcase into a vacuum (around 18” hg is common) and the hp gains in a 400 hp engine can be upwards of 20hp. Some smaller builds like 250 hp with them see as much 10 hp added. It is hard to quantify because those systems are usually done as part of a dry sump oil system with external pump eliminating the cam driven oil pump and doing those other charges add additional hp.
But the gain in hp from not having any pressure is simple to think of: how hard is it to push down a plunger (piston) into a sealed pipe, vs pushing it down an open pipe. If you have 1 pound (12”) of pressure behind the plunger and the plunger is 4” diameter- that means pie r2 - so 2x2x3.24= 12.56 pounds of resistance for that 1 psi. Now remove 12.56 worth of drag if you are at zero. Remove another 12.56 pounds of drag if you are as 12” vacuum. That is 25.12 pounds of force to your advantage. But you have 8 cylinders, so that is 200.96 pounds of force your engine no longer fights every rotation of the crankshaft.

There are drawbacks to crankcase under vacuum, so on a street car- absolutely not worth it. And the power gains of dropping roughly 100 pounds is where those gains in power and mpg are from.

To us, that will never pay for itself honestly. But in not burning our engine oil- especially if you buy more expensive (quality) oil, that WILL save you money. How long is the ROI? Varies based on cost, engine wear, annoyance of replacing leaky gaskets, etc.

 

[Big T]

Yea, some of the older oil fill had the vent pull from there. There is an oil splash shield in the timing cover. So by using 2 valve covers that dont have holes, and pulling the vent from the oil fill- he gets a more equal “vacuum” on the two sides of the engine.

All the oil condenses under both valve covers the same and pours down. The excess pressure- which is all you really want to get rid of, gets removed from the crank case in a location away from flying oil.

The entire idea is trap oil in the crankcase wether liquid or gaseous (mist). But the pressure has to come out of the crankcase. The pressure is created primarily from blowby of the rings. Then the movement of the pistons will generate some airflow and a tiny amount of pressure.

High performance engines actually use an external pump to suck the crankcase into a vacuum (around 18” hg is common) and the hp gains in a 400 hp engine can be upwards of 20hp. Some smaller builds like 250 hp with them see as much 10 hp added. It is hard to quantify because those systems are usually done as part of a dry sump oil system with external pump eliminating the cam driven oil pump and doing those other charges add additional hp.
But the gain in hp from not having any pressure is simple to think of: how hard is it to push down a plunger (piston) into a sealed pipe, vs pushing it down an open pipe. If you have 1 pound (12”) of pressure behind the plunger and the plunger is 4” diameter- that means pie r2 - so 2x2x3.24= 12.56 pounds of resistance for that 1 psi. Now remove 12.56 worth of drag if you are at zero. Remove another 12.56 pounds of drag if you are as 12” vacuum. That is 25.12 pounds of force to your advantage. But you have 8 cylinders, so that is 200.96 pounds of force your engine no longer fights every rotation of the crankshaft.

There are drawbacks to crankcase under vacuum, so on a street car- absolutely not worth it. And the power gains of dropping roughly 100 pounds is where those gains in power and mpg are from.

To us, that will never pay for itself honestly. But in not burning our engine oil- especially if you buy more expensive (quality) oil, that WILL save you money. How long is the ROI? Varies based on cost, engine wear, annoyance of replacing leaky gaskets, etc.

So given that I have existing valve cover with CDR, do I just plumb from that grommet?

 

[Will L.]

yes, that’s my recommendation. Try to come out of the cover vertically, then to where ever you place the provent.

On the provent, remember you have to set up auto drain OR you need to add a hose down to a ball valve and a cap at the end of ball valve. Clean the cap before removing, drain the oil, close valve and recap. Then pour the oil back in.

 

[Big T]

yes, that’s my recommendation. Try to come out of the cover vertically, then to where ever you place the provent.

On the provent, remember you have to set up auto drain OR you need to add a hose down to a ball valve and a cap at the end of ball valve. Clean the cap before removing, drain the oil, close valve and recap. Then pour the oil back in.

This is what they show on Amazon:

Amazon.com

 

[Big T]

Do I just cut off the pipe from the CDR and use that to stab into the valve cover grommet?

 

[Will L.]

Yes that valve & hose will work, keep it away from exhaust. Buy a cap that screws into the threads from any hardware/ plumbing store or Amazon. The purpose is keeping the valve outlet clean so you can pour the oil back in. No cap will attract dirt and contaminate the oil when you drain it into the container to pour back in.

If you cut the cdr, I don’t think the piece will be long enough to secure a hose onto.
I would buy a double ended barb fitting. One the size of the cdr nipple, the other the same size as the provent hose nipple. I’m not near mine to measure either cdr or provent.
If you can’t buy a one piece double barb fitting, then buy the two required sizes, with npt threads on the other side then screw them together using teflon paste or even rtv.
Do not use the entire cdr as the fitting as it’s restriction will fight the provent. Also you don’t want that immediate 90° fitting anyway.

If you buy a provent or cko provent that doesn’t come with hose, make sure you get hose rated for oil and high heat.

 

[Big T]

There is a product called “engine restore” that when tested shows slight improvement but won’t solve it.

For the blow by loosing oil- get rid of the cdr, install a provent200 in its place. (They make many sizes, the 200 is correct for us)
It is the most effective “catch can” available. You can buy the ebay knock off to save money, but throw away the ebay filter inside and buy the real provent filter. The only bay filter doesn’t work well, but the provent filter fits in the knock off housing.

You could modify the oil pan and make it an auto return but for this engine that is nearing death- I wouldn’t. Just check the can once a week and after a while you will learn when it’s full. Just drain it into a bottle and pour it back in the engine.

Amazon.com

Here is how to drain it to pour the oil back in. I suggest adding a thread on cap to the ball valve to keep it clean so you can reuse the oil.

Having trouble finding the Mann+Hummel Provent 200 for the price I'd like ($179). Which of the Amazon knock offs would work with the Mann+Hummel filter? Does this one work with the Mann+Hummel filters:

Amazon.com: Aramox Oil-Air Separator, Universal Oil-Air Separator Oil Catch Can Stainless Filter 3931030955 3931017950 for Crankcase Ventilation : Automotive

Buy Aramox Oil-Air Separator, Universal Oil-Air Separator Oil Catch Can Stainless Filter 3931030955 3931017950 for Crankcase Ventilation: Oil Tanks - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

 

[Big T]

I found a CKO Universal Provent 200 for $20.99 on eBay with free shipping. Order the drain hose and valve, plus 4' of high temp hose to fit the Proent 200 on Amazon. Will be gone from MT when some of this stuff arrives, but it's not an urgent project.

 

[Will L.]

Order the real inside “filter” piece. It is a crucial part of how it works and many have said the cko one doesn’t work well at all, but the housing is same size and is fine.
So long as the filter fits and seals where it is supposed to, you should be fine.

In next few days I will be able to dig out mine and compare measurements if no one else can or if you can’t find measurements from M&H online.