i order some autometer gauges(boost,pyrometer,fuel pressure), and i didn't do a search until i already ordered. i should've searched before, i know. but whats the problem with running isolators on diesels? i read that the vibrations will make it go bad quickly. what if you mount it on the firewall? i am stuck deciding between trying to make these work or sending em back and ordering some ISSPRO gauges. but i need some info. on these isolators before i make up my mind. any suggestions or infor. is appreciated.

 

An isolator is unnecessary and just one more thing to go wrong.
What good is a gauge that fails more often than the system it's monitoring?
Send it back or don't use the isolator.

 

why does it go worng, what from? i know it is not recommended to run fuel into the cab either.

 

Part of the issue with the isolators is vibration as you've mentioned, but most of the problem comes from the caustic nature of some of the additives in diesel fuel. The small bellows inside the isolators will soften and break down over time, and then diesel will simply be passed through the isolator anyway.

As far as running fuel into the cabin, thats a throwback to gasoline engines that has somehow made its way into the diesel market. Gasoline fumes can explode with some fairly common things you'll find in the cabin of a truck such as an electrical short or a lit cigarette. Diesel fumes just simply won't ignite like that. Big trucks have run diesel inside the cabins for YEARS and I've never heard of a single truck exploding from a diesel fuel leak inside the cabin.

Rod

 

so i should be better without the isolator?

 

I have Autometer Ultralite gauges, with isolator, going on 2 years now, and I have had no problem with my isolator except that the gauge tends to bounce a bit, and I am told this is because I have air in the line between the isolator and gauge.
The reason you want an isolator is because if the diesel fuel ever spills inside the truck you'll never get the odor out. You might not mind, but your passengers might.
Test it for yourself, take a diesel fuel soaked rag and put it under the seat for a couple of days and see if you want to use the isolator. (note, actually doing this may cause the odor to never go away also)

With electrical gauges I understand vibration is a problem, which is why many people put a flexible grease gun hose between the fuel system and the sending unit. Supposedly this helps.
I have never heard of a vibration problem with an isolator, besides my air problem.

One last thing, after I got my gauges I saw on the Autometer web site that they do not recommend their mechanical gauges be used with diesel fuel. I do not know why this is, unless it is CYA. As I said, I am happy with my Autometer mechanical gauges.

Chris

 

any air inside the isolator lines will cause your fuel pressure measurement to be WAY off.

Mechanical with no isolator is the way to go, IMO.

 

Can you explain the physics involved that will make the gauge read "way off" with air in the line? I have a diaphragm type isolator in mine and it has a few bubbles of air in the line. The manufacturer says that it won't make a difference. The only thing I can see that it would do is create a cushion as the air will compress and the antifreeze won't. I think it turns out to be a blessing in disguise as the pulses from the lift pump are dampened. With regard to the original question, I would definately use a diaphragm type as opposed to the piston type.

 

well thanks everyone for their posts. i am sending the auotometer gauges back, and i am going to be getting some ISSPRO's from usdieselparts.com, unless someone else knows where i can get some for cheaper. i am going to be running a mechanical gauge without isolator because i've read several people have had no problems out of them for many years. i also like the ISSPRO gauges better. i am going with the pryometer kit, fuel pressure gauge, and 60 psi boost gauge(in caese of turbo upgrade down the road, and it is the same price as the 40 psi). if anyone has some other advice they would like to share i would like to hear it. thanks

 

I went with the 60# boost gauge way back when..... now I have a 150# boost gauge.
You need to decide if twins and 450+ hp is in your future.

Chris

 

no. i plan on either getting a 14cm housing or a new turbo. will a 14 cm housing add more boost. will the 60 psi be overkill or should i stick with the 40 psi?

 

With the 40 psi guage, you'll be riding pretty close to the end of it (after mods, maybe even pegging it), with the 60, you'll be more in the middle for easier readings.


phox

 

With the ISSPRO"S, make sure you get the EV (enhanced vision) series guages....the older styles can be hard to read, especially at night.

http://www.isspro.com/proddetail.php?prod=R5604

http://www.isspro.com/proddetail.php?prod=R5623R

http://www.isspro.com/proddetail.php?prod=R3607VW

 

rattle_rattle,

Im not talking about a couple of air bubbles.......air in the line will cause erratic readings. As we all know, the electric guages can have problems with the senders, likewise most of the measurement problems that occur with the mechanical gauges are usually related to the isolators. Im not saying all guages with isolators read incorrectly. Im saying that measurement error is possible.

 

As for leaking diesel in the cab, I worry about it about about much as my home's water piping leaking in the walls, zero. As long as you do it correctly it won't leak. If you install a needle valve at the head of the system and run it closed almost all the way any leak would be a slow drip that can be shut off on the rare chance you have a leak. The needle valve opened just slightly will also prevent gauge pulsation and noise.