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turbo/exhaust system question

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I have an h3251vgt turbo that I picked up off of E-bay, and I don't know if the seals are damaged or not. There is a lot of oil residue out the front and back of it, but there is also some coked oil on the inside, and on the exhaust side of the turbo. There is little to no shaft play side to side, or front to rear. I am thinking that the oil coming out of the front and back is caused by cokeing clogging up the drain tube, and that the seals are not damaged. Is there a way to check if the seals are leaking, besides reassembling the turbo putting it on the truck, and running down the road to see if the seals leak?

I am also going to be redoing the exhaust system on the truck to make room for a future hybrid conversion/upgrade. I currently have a 3 1/2 inch exhaust system on the truck, and was wondering if I should reuse as much of the current exhaust as I can, or if I should go to a 4 or 5 inch exhaust instead. All of the performance upgrades I have are listed in my signiture. I will probably go to a #10 fuel plate in the future too.

Thanks in advance

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How much residue is on the seals??? If there is a lot, whip it down as far as you can. Then start it and go I wanna say maybe 15 miles or less. And then check again.. On my 98 I had the same thing, and I cleaned it, and come to find out it was the seals leaking.. Just a thought..

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Thank you for your input. I should have said that the turbo has not been installed yet. Dumb. I have an hx35 on there now, and will have to make a couple of adapter plates, and redo the exhaust before I can put the VGT on there I would like to avaoid reassembleing it, just to have to take it apart again to put in new seals. I wanted to avoid purchasing a rebuild kit as it costs $100, Ouch!:wall:

Maby you could answer another question. Should I go with a 4, or 5 inch exhaust? Would the 5inch be overkill?

I have to check with D.O.T. first, but I hope to run the exhaust along the windshield piller on the right side to make room for a hybrid drive system in between the frame rails.

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I have always read 5" is overkill until 500+ horsepower. It won't hurt you, but it really won't help you, might run a little cooler but your not going to gain much from a 4" to a 5" but a deeper sound. Not a whole lot of help, but it's all personal preference. If it was me I would go 5". Go big or go home :):thumbup:

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You are very welcome, anytime.. Sometimes I have pretty good ideas with things, and I am glad to give my input.

Well, I plan on going with a 4" with mine. Muddy talked me into it, just because I have to do emessions, and that way I wouldn't have to cut out my Cat. But you could do which ever you prefer, but for some reason, I would stay with a 4". You could go 5" but watch the CAT.

With everything else said, I would surely stay with a 4".

From the sounds of it, you have a good project on your hands.. LOL..

Dose this help ya?? It is something that I would do, but like I did say, it is really up to you in the end.. Hope it comes out the way you want it to. :thumbup:

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I have always read 5" is overkill until 500+ horsepower. It won't hurt you, but it really won't help you, might run a little cooler but your not going to gain much from a 4" to a 5" but a deeper sound. Not a whole lot of help, but it's all personal preference. If it was me I would go 5". Go big or go home :):thumbup:

I can see that from you.. LOL.. :ok:

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I would say go with the 5" if it isn't too much trouble getting it in there! I can't believe how much freeing up the 4" on mine has helped it. Seems strange though, as it didn't do much for my other trucks . . . . (Or did it? I think I need to go back and find their logs to see just where the mileage got better as to when I messed with their exhaust systems. Maybe I missed that before. Curious!)

I have wanted to try a 5" on my truck. I had a few wanting to talk me out of it. They were saying that I would loose needed back pressure and would actually loose performance and mileage. The performance loose has to be an additional lag when you first accelerate. Getting that larger slug of 'dead' air to start moving faster would make a slightly noticeable 'delay'. Couldn't be very long though! As far as loosing back pressure: I say horse dung! The turbo is the back pressure for the engine! To make a turbo work correctly and as efficiently as possible; it needs to be able to 'exhaust' from itself as freely as possible! 4" helps with this over 3" and 5 would have to be even better......

Without being able to run side by side tests with different sizes, I can't say how much of a difference these pipes would make. Bigger will improve performance, it is just a question of how much (Read: Will you be able to measure the difference!). . . . . . . .

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Thanks everyone. I will go with the 5in because the VGT should not need back pressure from the exhaust, as I can vary the internals of the turbo.

I think 5in will work better also as the exhaust is going to have a few bends when I rearrange it to go next to the windshield piller.

Hopefully, I can find some replacement seals for the turbo.

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I think I would go ahead and replace the seals too... My trucks first turbo only made it about 5,k or so before it started leaking oil. What kind of poor seals are they using to only last that long? (Must be the same supplier as the diff pinion seals! Front one went about then too . . . . Wonder if that is who makes the ball joints for them too?)

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