Always a good idea. Better safe than sorry. Mine have been in the glove box from the day I put the HPX line on.

 

I just bought an HPX stainless steel line from KCM Diesel Performance. Installed it very carefully but have small leaks where the tubes attach to the boss. Talked to KCM via e-mail and they suggested I tighten lines more but offered to send out a new line if that didn't work. I tried tightening the lines without luck and reported back to KCM a week ago. I have heard nothing back from KCM. They seem slow responding to e-mail. Will try calling next. I still have the line on hoping to hear from them but I'm considering pulling the line for now.

I liked the idea of the stainless steel line but noticed the OEM lines from the pump to the heads was a braided hose. I read that many HPX hoses had leaks and people were considering switching to the stainless steel line. What is the failure rate of the OEM lines from the pump to the heads if they are hoses?

Waiting to see what KCM says about the leaks. I didn't notice much or any difference with the HPX line as yet. Not sure if all the air is out of the system. I asked about a refund as well as a new line. Since I have not noticed much difference and facing leaks I'm considering returning the line if possible and putting the factory plugs back in.

Craig

 

Just got a phone call from KCM. Said they are sending me out a new HPX kit to correct the leak. There isn't any other posts that relate to my leak issue so I think a new kit should take care of the leak.

Craig

 

This post is FIY only - I thought it was interesting and just wanted to pass along some musings and mutterings. This is just another note in the "nothing is ever perfect and mechanical devices ALWAYS have compromises" file.

The stainless steel HPX line is a welcome alternative to the 'typical' flex HPX, since they tended to be so short-lived and unreliable. All but one, anyway.

In fact, I was almost ready to dump my Tymar HPX and replace it with a solid line, until I talked to a few people, including a friend who is a mechanical engineer.

Apparently, there are a few hypothetical, minor performance drawbacks to the solid line - NOTE: NOTHING CRITICAL AND NOTHING PROVEN !!

By hypothetical, I mean that when these (knowledgeable) people look at the KCM solid line, they think there could be minor issues, but it has not been confirmed or denied by testing.

Here are their musings - The solid line is a little longer than a flex line and has much sharper bends. Apparently, this might cause a restriction in oil flow from one side to the other, somewhat limiting the ability of the line to balance oil flow between the cylinder banks.

If there is enough of a restriction, it is possible that some oil in the HPX may take up semi-permanent residence there, never being able to quite leave the HPX before flow reverses direction.

My engineer friend also noted that a metal line would transmit more under-turbo heat into the oil, although I don't see how this could be harmful - after all, the solid metal fuel lines pass under the turbo as well.

Anyway, since I don't have the equipment or money to measure whether there actually is a performance difference (pressure balancing, not power) between the two, I doubt we'll ever know. In any event, I can't believe any difference between them would be significant - after all, stock there is no balance at all between the banks and any attempt at pressure balance must be an improvement.

However, since my Tymar flex line is rated to 400 degrees F and 4,000 psi, and some have been in service over 5 years, I think I'll hold out replacing it until it fails - assuming it ever does.

Just a few meaningless, meandering musings to mull over...

 

I just order the SS line from KCM.

I noticed that it said to install on 5 & 6. Is there any particular reason for this?

It seems that there would be more of a balance if it was installed between 3 & 6.

Just my thoughts, Any ideas?

 

I have a rubber one, that I had made.
I love it, and it only cost me 20 bucks.

I still keep the caps in the glove box just for grins.

 

5& 6 are opposing cylinders. they are directly across from each other. the reason it is used there is because of space, and it fits easily under the turbocharger. aside from the turbo, there is nothing to get in the way of the line at those two cylinders. get closer to 3&4 and the fuel filter bowl and rear of HPOP get in the way...

 

Oil does not need to flow through the line continuous to communicate pressure. The oil in the line can be stagnant (or nearly so) and still transmit pressure.

 

Doesn't the oil somewhat flow from drive to passenger from the reduced pressure of 6 and 8 firing one after the other? I would think even with the bends in the SS line that it would have no significant affect on oil flow, maybe at 2 or 3 PSI, but I know we are running much higher than that. I put on a SS unit as it seems like it would be more durable plus, I think it looks better imop. I do know that it helps quiet the injectors at idle so it is obviously doing some positive for the engine.

 

No, oil doesn't have to flow from one side to the other - but it does have to be free to move back and forth. In their view, multiple tight bends, which add frictional restrictions to movement, would reduce the ability to move and would slow down the back-and-forth pressure transfer - not eliminate it, but slow pressure transfer response.

I'm not saying I agree. I was only relaying other people's opinions. I'm also not saying they can't be right. As I said, this is the sort of thing that 1) testing would have to confirm/deny, and 2) either way, I doubt we'd notice any real difference.

I only put it up as someone's not-quite-in-agreement opinion.

 

Ok, ask your engineer friend what the pressure drop difference is going to be between hard line and soft line. My guess is that the soft line is going to "buffer" or absorb pressure increases enough to more than make up for the differences that the bends in the hard lines cause.
But that's just a guess, I only have a hillbilly engineering degree.

 

Yeah, I can't guess either, especially since I'm not a mechanical engineer - and I'm sure it very much depends on which soft line you are using, too.

 

I also have the stainless braided from dieselsite. was really nice to put in and did match the same material that factory installed for the rest of the lines...
I really cant see any difference since the line is only a little over a foot long.
I personally dont think there could be any measurable difference if the line only pushed 5 psi.. not to mention 500+ psi as far as buffering, I think there is really no line differnce because of size. its just there to equal pressure...it just depends on what you feel safer with braided or solid, my bet is on braided as flex and possible cracking and or rubbing.....just my 2 cents

 

Mine (steel HPX) arrived today. Will put it on and see if that noisey #8 shuts up a little.

 

Installed my HPX stainless steel line from KCM Diesel yesterday, just finished a 350 mile trip. Got to admit I was disappointed for awhile. Couldn't tell any improvements at all. After 50-60 miles I noticed a much quieter idle. Even my skeptic wife admitted it was less engine noise at idles and slow speeds. I even have her convinced that the muffler delete quietened the cabin down.