TOPIC: 2002 Corvette LS1 Update and need advice.

I'll try to make this short. Rob Corvette owner had oil leaks. Hired a mechanic to look it over and put the PCV valve to the way it was. Saw the various testimonials on Youtube. Got motivated again and wanted to put a cap on the vacuum line. This was last night. Bought brand new vacuum caps for it too. I just want to make sure I did it right.

We located the PCV Valve. This PCV valve setup is a bit weird. I found the LONG vacuum line. It goes from the driver side to the passenger side and into the intake manifold. Took off the small PCV hose attached in the middle. Capped that end and the other end the vacuum connector on the intake manifold. Is what I did correct?

Before I capped it. I took it off and did not feel like it was the vacuum line. I put a shop rag on it to see if it would hold the shop rag. It did not. Is this normal or not normal? We had Rob's friend a engine tinkerer point out that it was the vacuum line. He was not sure why no strong suction. I made sure it was NOT the positive crankcase vent and had Rob's friend verify as well.

Also we did not touch the battery. Ron did the groove on this Corvette a while ago. But I wasn't sure if I needed to drain the ECU while capping off the vacuum line.

He took it for a test run and did the conditioning. He has a built in MPG digital gauge in the Corvette. I did not go with him on the test run. Had to go home. He told me at first his mpg increased to upper 30's. Then when he turned the corner went down to around 20 mpg.
I told him the computer will readjust.

I hope I did everything right. Hopefully someone will address my concerns. Thank you.

Juan ya know what they say--a picture is worth a thousand words. Pics of this would really help. Pics of before/ after any mod would be easiest to analyze.

The MPG readout on dash will fluctuate w/ load and driving conditions.

Tracy G

Hi Juan,

Something to keep in mind with all computers that are calculating MPG's

They do not know what the Groove is doing to the engine so the best way
to get those numbers is the old fashioned way.

Fill the tank to the click-off, run it, refill to the click-off and check
the miles against the gallons.

Karl Fortner
Tacoma, Washington

Hi Juan, sorry we didn't get to talk the other night!

Anyhow--I've only worked on 2 Chevy vortec 5.3 engines, not a 'Vette. From your description the PCv system sounds the same. PCV mounted on top of intake, it Is the vacuum source, it's bottom is mounted right into intake plenum. So only place you'll feel suction is the end of the nipple on PCV itself. So you capped the PCv itself, then tied that hose from driver side valve cover over into the pass. side valve cover breather hose, then the remaining nipple from this tee into the air duct...right?

Tim from Redding CA, posted great pics of the same thing in his recent post about Grooving his wife's Suburban when he was here last week. Those pics he put up show a textbook example of how to Tee those 2 hoses together and then run to the air duct before the TB. He and I agreed it better to cap original nipple on TB where Breather hose originally went, and run hose to air intake duct. We felt the suction on the TB nipple would be too likely to pull oil from crankcase, and since suction in air duct would be less that was place to run the hose to.

Check those pics out, then see If what ya did on this Vette matches!

Call me again if ya want, I'll be more available for several days.

Tracy G

Good news everyone! After a long struggle Rob the Corvette found the vacuum. He has capped off the PCV valve and the vacuum line. The vacuum line is attached to the throttle body. He capped it off the vacuum line and telling him over the phone. I told him to take off the PCV Hose and put a cap on the PCV valve. At first he put a cap on the PCV hose and wasn't sure why he needed to take off the hose.

He is a confused. He thought he was going to get immediate results. Since I have showed him the youtube videos of the various people loving the Gadgetman Groove done to their vehicles. I told him what Ron told me. Every car is different. I asked him about performance but he told me it's hard to tell since it's already a fast car.

The attached picture of his MPG digital gauge. He was getting 35 mpg in the freeway. He really is hoping for more MPG. He wants to get 40 mpg.

@Tracy: Remind me again why to reroute the PCV line? Rob is a hard guy to convince. He would like to keep it the way it is now. Just capped. He would change his mind if you tell him he will get more power and better gas mileage.

Is there anything else that someone here recommends? I hope there is.

Ron, if you are reading this. Please disregard the last email I sent you. Also I hope you are feeling much better.

OK I'll try this again.

Capping PCV Valve means: to cap or seal the MANIFOLD Vacuum Source to PCV Valve.
This eliminates a big source of manifold vacuum loss (vac. leak)

We DONT just seal off the Crankcase Ventilation system. Crankcase MUST BE VENTILATED

Sealing the crankcase will result in pressurization--therefore oil leaks.

You must understand how PCV/ crankcase ventilation system works to understand this mod. Period.

It's a flow-through system. Fresh filtered air enters crankcase through the Breather hose on one valve cover.(On this 'Vette engine the way the Factory did it--the fresh air is drawn from the nipple on pass. side of TB in pics).On the 2 Vortec engines I've worked on the flow path was like this: Fresh air drawn from nipple on TB Pass. side, then goes through hose to fitting on Pass.side valve cover. This air mixes w/ crankcase gases and oil/water vapor inside crankcase. Crankcase fumes drawn out from fitting on Driver side valve cover thru hose to PCV Valve. On the Vortec's the PCV Valve is on top of intake manifold at center top. ON Vortec's the PCV Valve is in a grommet, the manifold vac source is the bottom of PCV, it's a 90 deg. righr angle shaped PCV Valve.

This Vette engine has the same system, but it's built different than the Vortec's I've seen. PCV Valve is a straight inline type acting as a hose connector to 2 different size hoses.

SO- fresh air enters thru Breather, picks up crankcase fumes, is sucked thru PCv Valve into intake manifold then burned in cylinders. Often, the Fresh air side of the system is called the Breather side, the dirty crankcase fume side the PCV side, just to spell it out.

Now, its possible to just cap PCV manifold vacuum source, and leave hose(s) open to atmosphere to ventilate crankcase, maybe even put small filter on end of hoses where fumes go out.

BUT---BUT!! This is bad practice/karma, venting air pollution AND violates Emissions Regulations. Plus doing this--water/dirt can/WILL get into engine! Even w/ K&N type filter water goes right thru those!! It's also not necessary. Don't do it this way!

Remember PCV valve can be factory installed in different ways, inline in a hose, on a valve cover, or directly to intake manifold. Does not matter. Figure out which end of PCV Valve is hooked to manifold vac. Remove hose w/ engine idling, you will feel suction, engine may speed up or die(it's a BIG vac. leak) Now you can tell what to cap off.

Looking at these 3 pics--I can't see the entire hose system/ connections. Here's what I would do and why:

Determine which side of PCV Valve is vacuum, cap that end securely. Now find the vent. port/ hose nipple on both valve covers. I'm not certain, but this engine may use a vent for crankcase that's not on valve cover, maybe 1 on valve cover one elsewhere. You guys gotta figure this one out. Using hose/ tee's connect those crankcase vent ports to the air inlet duct. I would cap off the factory stock breather hose nipple on TB side visible in pics. I would try to install a new metal or plastic hose nipple into the main large dia. air duct going to TB, some distance away from the TB itself. Also I would try to increase hose ID where possible or legnthen the hoses, or both.

That Breather hose nipple on side of TB can get high velocity air moving past it and could cause oil aspiration thru re-directed hoses into TB. If you use larger ID hose connected to main air inlet duct, the velocity of the fumes from crankcase will slow down and likely reduce oil aspiration.

This re-directed crankcase ventilation system may still draw some oil/water vapor and liquid oil. So it needs checked frequently, just pull hose off nipple to air duct and look. MAY need an air/oil separator, you have to see if it will. This 'Vette hi-performance engine is a Heavy Breather for sure, esp. on heavy accelleration, and needs adequate crankcase ventilation. I would expect some oil aspiration. Remember this engine has ALWAYS been aspirating some oil/crap thru the PCV, but INVISIBLY.

So WHY Do all this. Because this will enhance the Groove effect!! I've seen excellent results from the PCV re-route on a car I own, all on its own. Ron's original idea w/ capping PCV is to increase manifold vac. intensity, in BOTH directions, hi/lo vac., IMHO. All the rest, the hose re-direct, the air/oil separator, is to eliminate possible problems, and keep the engine, vehicle owner, Environment, and EMISSIONS AUTHORITIES Happy. Do it right, and Everybody goes home to Milk and Cookies, dig?

Juan, ya can still call me if ya need to!

Tracy G

Thank you Tracy! For the lengthy explanation here and on the phone! I just talked with Rob today and he told me it's leaking again! He took off the vacuum caps and went back to normal. So he will try PCV reroute. He does not want to do the "catch can" option. He is willing to do the PCV reroute. Anyways what supplies does he need to buy and where to buy them from? AutoZone, NAPA? He has a local mechanic that he trusts. Hopefully he will know what to do with this.

Tracy can you please share with myself and everyone on these forums the step by step process on what to do? I'll bet this will help out a lot of people.

Sure, Juan, it's simple. All needs to do is get several feet of hose w/ same I.D. as existing PCV and Breather hose. A Tee to match that I.D.. A brass or plastic hose nipple that fits the hose, w/ pipe threads on other end of nipple. And vacuum cap to fit the vacuum fitting that leads to the PCV Valve, and another cap to cover that nipple on pass. side of TB/or manifold where stock breather hose connects.

After that, one must understand the direction of flow in this system to do it right. PS-it would be good to increase the I.D. of the hoses over stock, as this will slow down flow velocity in these hoses, and could reduce likelyhood of oil aspiration. Heater hose would be likely best choice.

I'm guessing this guy likes to romp this Vette, it IS a 'Vette, after all!

check GM Tim's posts, there a great pic of the hoses T'eed together and going to a brass hose nipple installed in main air intake duct, w/ the stock breather hose nipple on TB capped.

I still think there is an issue if oil is leaking or in the stock hoses, but if he wants no air/oil separator, well it's HIS car after all!

Tracy G

@Tracy: I have a few diagrams that hopefully will help you out with Rob's Corvette.

Thanks Juan, the bottom diagram tells the story, now I understand this one!

We will see what he says after a few hund. miles, after having cleaned the air intake duct and all the crankcase hoses out. Simple system once ya see it!

Tracy G