I borrowed this from a thread Cow Racer listed on the Page words to follow, same thing I & others have said, this one with hidsight sorrows read & heed.

I managed to sneak in a few hours on the truck engine this weekend and I know what happened to it now.

The problem was in the #3 cyl. I knew this even before I pulled the engine out of the truck. But I didnt know what the problem was. After getting the drivers side head off, the cause of the failure was clear.

The #3 piston had a longitudinal crack in it running from the 9 o'clock position to the 3 o' clock. It nearly transversed the entire piston, stopping only about 1/2" from the 3 o'clock side edge. The crack allowed combustion gasses to escape through the piston. This eroded a hole in the piston aprox the length and thickness of a quarter at the top of the 'fire slot' between the 'mikey mouse ears'.

The cylinder itself had minor scuffing on the 6 o'clock positon, probably due to some piston material getting lodged in the rings. It is not too bad and should clean up with a .030 overbore which I was going to do anyway. All the combustion chambers had the typical cracks between the valves. Nothing too serious.

Cause of the destruction of the #3 piston is probably due to high EGT's. I foolishly ignored the advice given time and time again to get gauges first off. I ran mine with higher boost and a chip for about 4 months before I got gauges. The first time I saw the EGT's I was getting just going hard up an onramp, I realized that I probably overcooked the engine on numerous occasions. Now that particular chicken has come home to roost

The $4500 Moral of the Story is:

GET GAUGES FIRST! If you are even thinking about a chip or boost control of ANY kind, get the gauges first! Don't be an ass like me! If you think you can't afford gauges, do you think you can afford a new engine?

Tim

--------------------
>94 3500 Crew-Cab Dually. Currently INOP with a bad motor
>Turbo-Master and Heath Max-E-Tork chip
>Kennedy 3.5" Exhaust
>Eagle Alloy Wheels
>Isspro White-face Guages
>Bosch Marine High Flow Injectors
>Hoosier-Tech FSD Cooler (home-made)

Hind Sight is 20/20, its always better to learn lessons like these second hand too ;)

Gauges, gauges, gauges. That's what everybody should know about diesel engines when you want to start bringing the "FUN" out of 'em!


Big HOOYAH! to Cowracer for sharing his own "I told you so" story. That always takes big ba!!s.

Ah yes, the infamous 9 o'clock to 3 o'clock crack. This is the way 6.5 pistons will usually crack. The question is, where does the crack start from? I have seen many 6.5 pistons cracked this way, but I have also examined other pistons from the same engine that at first didn't appear to have any cracks and then looked a little further just to find that there were cracks starting to form in the wrist pin boss, hidden from sight. It is possible that this is where some of the cracks start and then continue to travel until the top of the piston is cracked. Notice that the 9 o'clock and 3 o'clock positions line up with the top of the wrist pin? These cracks could be caused by a combination of too much boost and too high egts. Very expensive none the less. My first case of cracked pistons was to be blamed on POST TURBO pyrometer probe. I never exceeded 1000 degrees post turbo, but I can guarantee you that there was much more than 300 degrees tempature difference! If I learned anything from this at all, it was to only run the probe, PRE TURBO! On another note, I patched that engine back together, because I had to and it ran good for another 50,000 miles, I am ashamed to say how much I had to hone the #8 cylinder to clean up the scoring, and I don't even think it was very round, but it ran. On that particular engine, at the time of that untimely cracked piston, I replaced a total of 4 pistons due to cracks. The one obvious one and three others that had cracks starting at the top of the wrist pin boss. These cracks were only apparent with the wrist pin removed. The bad thing is that I must have missed one, because 50,000 miles later another piston cracked through the top, and it was one of the pistons that I didn't replace. Later I found cracked main webs in that block and it was a favored 599-:t . Live and learn.

Damn doc! You beat me to the punch on my own story! I was gonna post it here, but I didnt get a chance yesterday.

I was asked how high I think i got the EGT's before gauges. Seeing how quickly I can get them up to 1200 (pre turbo) and remembering how hard I was getting into it before gauges, I would guess that I was north of 1500 degrees MANY times.

What really hurts is that the $4500 that I am having to throw at this thing was my down-payment for my Harley-Davidson Road King that I lusted after for the last 5 years. :bawl:

Tim

I get fussed at now and again for posting same info at the 2 different sites, here or there, but where appropriate if important & I think it needs to be shared for the good of the 6.5 owner community I'll bend the rules a little.

My hat off to you Sir for fessing up to a learning the hard way experience, don't feel alone in this, many of us self included have to run into brick walls face first before seeing the better idea is to go arround it rather than thru it.

So where is the best deal on a pyro gauge? And what range on the gauge is necessary for a pre-turbo install?

I don't really want to hear where everyone else bought theirs. I just want to know how to get it done for the least amount of money, whether it's an all-inclusive kit, or you have to buy fittings & tubing seperately at different places. Pyros are spendy S.O.B.'s, and I really don't tow anything other than my boat a few months of the year, but I've been running without one long enough.

Search the net also look at boat and aircraft instrument sites, pyro is pyro at the end of the day, Summit, Whitney & Jegs generally due to volume of business they do have attractive pricing. Don't forget to call site sponsors/vendors ask for theirt best price you might be surprised in the positive if you don't ask you will never know.

0-1500F is a good range for pre turbo, 0-2000 post turbo, generally not always though the smaller the range of scale, the more accurate the reading. Several digital models worth a look as well now that electronics prices are coming down.

A simple K-type t-couple and 0-1500deg gage is cheapest, around 60 bucks - requires only lighting power, so will indicate cool-down temps with ignition off.

If face is colored for operating-caution-danger ranges, pre-turbo coloring is lower by ~300deg than post-turbo.

I have one electronic pre-turbo, and one standard, as described, post turbo - generally defines ~300deg drop across turbo.

The temp drop is caused by the exhaust energy required to power the turbine.

Do you tap right into the exhaust manifold for a pre-turbo (or in the cross-over)? Where exactly on the manifold?

(I just had that wheel well out last week to replace glows. Wish I would have been thinking ahead a little.)

Was it EGT's or high IAT's coupled with 21.3:1 cr.
Goodthing a cracked piston is fixable.

I was running EGT's post turbo of 1200F, never kept them there for more than 30 seconds tops while pulling my 7200 lb trailer @ 75 MPH, it had a slight miss since the day i bought the truck and i'm sure nobody else would have noticed it, got the truck from a farmer that pulled a horse trailer with it frequently and i'm sure he ran it pretty warm a few times but was all being controlled by factory ECM at the time. Point is i'm sure that since reflashing and doing my previous mods i probably sped up the miss so it was even more noticable until i decided to park it and have a look inside, i think i was lucky not to have cracked a piston yet and was also lucky i still had the 95 to drive as not everyone has a spare unit when theres goes down. I'm near 100% sure that i had a couple of cylinders having a little chit chat with each other through the head gaskets and hopefully once its back together the miss will be gone and power restored. My EGT probe will now be pre-turbo and with the increased fuel of the 92mm pump i will most likely be putting in an IC soon after its back on the road, until that time i'll have to use the ECM on my shoulders to control things.

The post- probe is less than an inch below the turbo elbow\down-pipe flange.

The pre- is in the driver-side bank exhaust manifold turn-down, 'bout half-way between cyl#7 port and the crossover flange - drilled and tapped for 1/8"npt, probe inserted to 1/2 area depth.

That location represents true EGT, prior to passing thru the cross-over pipe, where EGT is cooled by constant road-draft.

The cross-over pipe is, after all, a simple one-tube heat exchanger - think about the effect of winter-time temperatures, freezing road slush.

Passenger-side Exhaust Gas Temperature is average of that bank, and cooler flow thru the c\o tube from driver-side bank - a lot cooler in winter climes.
Particularly so, north of the 'it don't snow much, down here' line.

All imo, of course...........

Thanks a bundle gmctd! I'd guess that location makes for the shortest wire too.

FYI:
Heath $155
SSDiesel $155
Kennedy $148

They're all right about the same. :cool:

Holy pyro's, batman - that's some hi-temp pricing!

'djoo try Isspro, Banks, etc?

Hell, I woulda paid $155 to have someone to slap me in the face and make me buy gauges back then at TWICE the price. Of all the human laments.. "If only I'da known" is the cruelest.

Get gauges! Any way you can!

Tim

Yeh, I feel fer ya on that Hog deal - my choices are Hog, or a tractor with hydraulics with front-loader and back-hoe.....and I'm talking about the kind of ho' used for diggin' and makin' trenches in the dirt.;)

I kinda like the stock idea myself. . . I know, I'm no fun. I can't find the RPO code for the parachute, gotta keep lookin.:idea:

GMCTD,

Can you please post a picture of where you put your pre-turbo probe? I have been nervous nellie on drilling for my pre-turbo probe. I looked at where JK says to put it but on my rig, I don't see how to get it drilled let alone while the damn thing is running!!http://www.dieselplace.com/forum/images/smilies/biggrin.gif

dps-performance.com has a good price on isspro pyros.

Get all your items together, prepared for immediate use

drill motor and installed bit, sized for 1/8"npt tapped hole
1/8" npt tap
Extension power cord, if required
cardboard to lay on
safety glasses and full face shield
thermocouple probe and npt fitting

where you can use it immediately upon starting the engine.

Start the engine, from cold start, so it is idling at cold.

slide under the truck, wearing eye safety equipment, drill the hole, then tap it.

Normal exhaust pressure while engine is running will blow shavings out of the drilled hole, and also while you are tapping it.
The manifold is cast iron, so the shavings will be very small curli-ques, usually around 1/32" or so.

Full face protection is required, including ears - exhaust gas temperature is around 275deg at idle, and you'll get about a teaspoonful of chips..

Run the tap in about 1/3rd, on a short tap, then try the tubing fitting for makeup.
If it gets a good tite seal at about 1/2 depth, leave it in, kill the engine.
Use no teflon tape or paste - if anything, hi-temp loc-tite pipe sealer is ok, but will seal without it.

Run your t\c probe in all the way, then back it out by half, cinch the nut down and you're good to go.

Still neeed to get my son over to show me how to do pics, so I don't have any for now, but -

Looking up from the floor, the driver-side exh manif curves down just past the #7 cylinder port, toward the cross-over flange.

I drilled\tapped that inside arc about midway between the port and the flange

.

GMCTD, Can you please post a picture of where you put your pre-turbo probe? I have been nervous nellie on drilling for my pre-turbo probe. I looked at where JK says to put it but on my rig, I don't see how to get it drilled let alone while the damn thing is running!!http://www.dieselplace.com/forum/images/smilies/biggrin.gif
I was going to post the exact same question this morning. Thanks nvmtnlion and gmctd!

I bought my auto meter # 2654 from summit racing.
Auto Meter Z-Series Analog Gauges,
Gauge, Z-Series, Pyrometer, 0-1,600 Degrees, 2 1/ 16 in., Analog, Electrical, Kit
$135.95

I got mine from usdieselparts.com #R3707GKIT was the part number and it was $125

About a hundred on egauges.com for the cheapest isspro kit they carry, $150 is not bad for a better gauge.

The turboside exhaust has two bosses, one on the side facing the block and one on the outside just under the turbo flange.

And thanks again to gmctd for the isspro he sent my way. I may not have ever gotten one otherwise and it has become one of the main gauges I look at when I'm wondering "What's happening?" as I drive.

I put my second/new one on the driver's side right as it turns down into the crossover. I seem to be getting very fast accurate results.

Get all your items together, prepared for immediate use

drill motor and installed bit, sized for 1/8"npt tapped hole
1/8" npt tap
Extension power cord, if required
cardboard to lay on
safety glasses and full face shield
thermocouple probe and npt fitting

where you can use it immediately upon starting the engine.

Start the engine, from cold start, so it is idling at cold.

slide under the truck, wearing eye safety equipment, drill the hole, then tap it.

Normal exhaust pressure while engine is running will blow shavings out of the drilled hole, and also while you are tapping it.
The manifold is cast iron, so the shavings will be very small curli-ques, usually around 1/32" or so.

Full face protection is required, including ears - exhaust gas temperature is around 275deg at idle, and you'll get about a teaspoonful of chips..

Run the tap in about 1/3rd, on a short tap, then try the tubing fitting for makeup.
If it gets a good tite seal at about 1/2 depth, leave it in, kill the engine.
Use no teflon tape or paste - if anything, hi-temp loc-tite pipe sealer is ok, but will seal without it.

Run your t\c probe in all the way, then back it out by half, cinch the nut down and you're good to go.

Still neeed to get my son over to show me how to do pics, so I don't have any for now, but -

Looking up from the floor, the driver-side exh manif curves down just past the #7 cylinder port, toward the cross-over flange.

I drilled\tapped that inside arc about midway between the port and the flange

.
Excellent post GMCTD. I have just a couple of questions before I'm ready to put my new gauge in (just arrived today).

1. Do I just assume my npt fitting it 1/8? I don't see any description or identifying label on it, and there's none in the instructions that came with it or on the Isspro website.

2. What size hole do I drill?

Thanks!

Wade, my gauge set (part # listed above) came with a 1/4" NPT thermocouple. The hole size you end up with will be written on the tap you use.

Piping to NPT standard is measured by inside diameter -
1/8"npt will have 1/8" hole thru - pipe is .405dia

1/4"npt will have a 1/4" hole thru the pipe, is .540dia

3/8"npt will have 3/8" hole thru - pipe is .675dia

Normally, a 1/4" t\c probe would have a 1/4" tube x 1/4"npt fitting, about 1/2" dia, requiring a 7/16" drill for tapping

I used a 1/4" tube x 1/8"npt fitting drilled thru, which requred an R drill for tapping

Okay, all of this talk I am going to get all my stuff ready and I am going to drill on the flange just below the turbocharger on the outside (towards the fender well) I have done all the necessary work to get ready. I have tools, cutting oil, welding gloves. I have seen what it takes to drop the fenderwell out of the way. I have checked ebay for a replacement manifold incase it cracks.

Wait a minute.. GMCTD ya mean I don't have to use the 1/4" fitting it came with?? Please elaborate?

That 1/4"t x 1/4"npt is a common size, evereyone uses it, but 1/4"t x 1/8"npt is available, allowing smaller drill size for tapping.

Just drill the fitting with a 1/4" drill, just like the 1/4"npt fitting, so the t\c probe fits thru.

It'd take a major malfunction to crack the exh manifold in that area, tho

Cool http://www.dieselplace.com/forum/images/smilies/rockon.gif I will go look at Lowe's tomorrow and THEN drill.

Normally, a 1/4" t\c probe would have a 1/4" tube x 1/4"npt fitting, about 1/2" dia, requiring a 7/16" drill for tapping.
This is the exact setup I'm going to install tonight. What size tap do I need to buy?

I got the 1/8" npt male to male and drilled through it 1/4" and found a tap for it at lowes for $8.

When you look at taps on the shelf at the hardware store each sized bit will have the right tap in the package. Take the 1/4" fitting as most places have a gauge for size/thread right there.

I believe it is 11/32 drill for 1/8" tap. SEARS is cheaper than lowe's, at least in my neck of the woods.

Watch the treads on the taps. The set of ISS Gauges I got have the brass fitting with a pipe thread. It's the piece that goes into the manifold which the probe screws into. Could be an issue.:eek:

You will need a 1/4"npt tap, Wade, based on your description.........

You will need a 1/4"npt tap, Wade, based on your description.........
What a screwey nomenclature. It's called a 1/4" tap, but it's almost a 1/2" diameter. Confusing. So what do they call a tap for a fitting with a 1/4" I.D. hole in the middle, but has a larger or smaller OD?

I bought the tap over noon hour. Says on the package it's a 1/4" tap for a 7/16" drilled hole.

NPT stands for National Pipe Thread.

Basically 1/4"NPT is for 1/4" I.D. Steel pipe. Also, the threads have a taper to them as opposed to standard bolt threads.

IIRC a 1/2" pipe is ~7/8" O.D.

To install a thermocouple, you will need PIPE taps and if your tap says you need a 7/16 hole, then you should be good.

Tim

Got the pyro installed tonight, per GMCTD's suggested location. The gauge reacts almost as quickly as the boost gauge.

I didn't have to use any of the lead wiring. I'm going to see if I can send it back for a refund.

Install took me about 3 hours, start to finish. Didn't think that was too bad for a first time.

Electrical rigid conduit is pipe dimensional, also, but taps are strait threads, non-tapered, allowing fit-up adjustment.

Water\gas plumbing is tapered thread, for sealing the connection.

Pipe\conduit is measured inside-diameter

Tubing is measured outside-diameter

Don't even get me started on other things guys are measurement\dimensional conscious of..........

LOL GMCTD, ya mean things like HORSEPOWER claims?http://www.dieselplace.com/forum/images/smilies/muahaha.gif