It still seems odd to me that your coolant temp is rising that fast. Even with your high EGT's it seems like something else is wrong. Timing could be it, but still doesn't add up. The only thing I can think is that you have a hot spot in the motor somewhere, but don't ask me where. Just curious, how well do you keep up on the coolant? If the pH stays off long enough it will create cavities around the cylinder walls, which could be the hot spot. Its not normal for your coolant temp to spike as quick as your making it sound. Also, how clean is your radiator, and are all your fins straight? It should have more than enough capacity to cool your engine, even with the fuel you're running. Make sure its not obstructed, partially plugged, or wrecked from the fins being closed up.

 

How long is a "flash"? 1 minute, 5, 10? Are you aware that compressing air causes heat? If you are compressing the air to over 30 lbs of boost than there isn't much cooling availability left in the air once it gets to the radiator. What RPM is the engine at? The lower the rpm, the less water that is flowed thru the radiator and the less air is pumped thru the engine. For instance, with my 5 speed towing at 60 in 4th gear will result in a lower water temp (and EGTs) than 60 in 5th. Finally, is the only additive to the water the Royal Purple? I'm pretty sure I read somewhere that antifreeze dissipates heat better than plain water.

 

You caught me thinkin' again. I always get in trouble when I think.

I may or may not learn from this so keep your eyes on me


crucescrawler I understand you do not want to give up fueling right now.

Let's start diagnosis by cutting fuel back. If the coolant temps stay down, we all know what to do. If not, you keep plugging forward until we get a diagnosis. Reducing fuel does not cost any money either.

Ronnie

 

Well put Ronnie....no one really wants to reduce fuel but it might be nesissary for a diagnosis. Sometimes you have to take a step back to leap forward.



Travis

 

Everything is new, radiator water pump, fan clutch, & t- stat... coolant as well, distilled water and royal purple.

 

Okay, I moved my pyro to pre-turbo and ran the truck unloaded down the road a minute ago... yep, it looks a lot different when you actually see the guage spike, due to the obvious heat dissipation process across the housing before you just can't see what is exactly going on. I relocated it per piers diesel specs. 2'' from the flange, 5/8'' from the center towards the firewall. Yes, thank you guys for not letting me run it like that. I am glad I don't have to be stuck on the side of the road, with nothing but " I wish I woulda listened" stuck in my head.
There is also new coolant as well as the additive... I hammered it pretty good a minute ago, and I saw 1400* hit the guage. I can understand If I am constantly pulling my load at peak boost up hills and I was seeing 1400* without a load a second a go, my engine will get hot. Now, as for the "flash" once I am at operating temp. (180*) it will creep up slowly to about 210* if I monitor it, and go about 60mph but will crank up fast if I keep my foot in it and try to run 70 mph or stay with a hillclimb. Once again, this is only when pulling a load (max. that I have pulled is about 13k) that the engine wants to get real toasty. Just for an idea of how bad it is, I top hills at 45-50mph burning up, and nerve-racked and stock vehicles will pass me with a similar load with no problem at all.
Thanks so far guys, this is really helping me get a feel for this.

 

Big difference in temps huh? I never trust post-turbo. It's more of a dummy gauge at that point. You're lucky you didn't melt anything. I can't imagine what your egts must be while pulling a load if you hit 1400 empty on flat ground. They say the max sustained egt is 1200 degrees.

 

I know it... Now anyways.
I am gonna turn it down tonight and hook up to a skidsteer. I think I will start by shifting the plate back .100" and jot down my results. I don't want to shift the AFC housing, or crank on the star-wheeel yet. I think that by keeping a log of my results should help me pinpoint where I need to be at Just let me know if this is the right approach. Is the #8 plate the one I need to be fine tuning for a tow vehicle?

 

Well considering aluminum melts at 1220*F, you're probably in trouble. I still think you got a hot spot. Once cavitation starts from bad coolant, you can't reverse its effects. Unfortunately theres not much you can do about it if thats the case.

 

The parent bore blocks on the BT engine are pretty thick. Cavitation is usually a problem with sleave bore engines like the PSD and DM where the liner sleave is exposed to the coolant. Vibration from the firing events in the cylinders causes the bubbles to collapse and that causes the cavitational damage to the liners. The larger Cummins engines run additives to the coolant to reduce the build up of these bubbles.

The aluminum is work hardened in the engine and the surface of the piston would only see 1400+ degress for about 1/8-1/4 of its time in the engine and is oil cooled from the bottom. Sustained running at 1400 would cause eventual damage to the piston crown edges and ring lands and liner scoring.

With those EGT's I forget what the peak boost was... I think more that timing may be one of the issues here.

 

I think your stated melting temp is a little low. I've heard 1300 to 1350.
At any rate, your worries about coolant cavitation is unfounded. From

http://www.turbodieselregister.com/t...ntifreeze.html


Q1: I’ve often heard the term “cavitation erosion” in the same sentence as diesel engine. What is cavitation erosion?

A1 With a term like “cavitation erosion,” you might think those affected would be found in the waiting room at your dentist’s office. Not so. Cavitation erosion or liner pitting, if left unchecked, is a real issue with some diesel engines. Okay, I guess there is a parallel to your dental hygiene. A cavity is a cavity, and both types can drain money from your wallet.

To further clarify the issue, you may have noted that the cavitation erosion is an issue with some diesel engines. Which ones? All diesel engines with wet sleeves are subject to cavitation erosion or liner pitting if the cooling system is not properly maintained. The wet sleeve design means the cylinder liner can be removed and replaced in the block. Although the cylinder liners are pressed into the block, wet cylinder liner design does not have the same structural rigidity as a cast block design.Under-concentration of coolant treatment additives will result in liner pitting and engine failure.

The Cummins B5.9 and 6.7 liter engines are a cast block design and do not have wet or removable sleeves.

To add further explanation to the liner pitting phenomenon, I’ll quote from a Cummins Inc. Cooling System brochure. “Liner pitting is caused by vapor bubbles formed when the piston strikes the liner during engine operation. The energy generated during the combustion process and the side-to-side motion of the piston causes the liner to vibrate at a very high frequency. The liner moves away from the coolant fast enough to form vapor bubbles.

“The vapor bubbles collapse against the liner surface as the liner moves back into the coolant. The implosion of the vapor bubble against the liner surface produces a very high velocity jet of water. This water jet removes material from the liner surface. The jet of water acts on the liner surface with a pressure exceeding 15,000 psi. This process repeats again and again, resulting in liner pitting.”

Q2: Is cavitation erosion or liner pitting a concern on my Turbo Diesel?

A2: No. Again, the Cummins B5.9 and 6.7 liter engines are a cast block design and liner pitting is not a concern.

I'm sure there are plenty more sources for the same info. Bottom line, don't confuse a Cummins with a Powerstroke, or a D-max for that matter.

 

To the previous 2 posters, and the original poster. I know how rare cavitation is on the B-Series engines, but not knowing how the PO took care of the vehicle always leaves something open, and considering the post-turbo pyro, and the symptoms the OP is complaining of, its still a possibility. I have 855's, 903's, N-14's, etc that I HAVE to worry about this stuff with, while I don't worry about it on my B-Series, its still no excuse not to change your coolant, because it CAN happen (no matter how unlikely it is, we've all seen things on this forum we didn't believe could or would happen). Just beacuse the block is cast does not mean vibrations don't transmit from the cylinder wall to the water jacket. Yes, a sleeved engine is MUCH more prone to cavitation, but again, it happens to anything with a water jacket.

Aluminum melts at 1220*F (roughly, +/-20*F), and with the OP talking about seeing 1400* with his new pyro location, its very likely that he has sustained temps well over the melting temp of his pistons. While the case (shell) of the piston is work hardened, sustained temps WILL fry a piston... I'm one to know, I just burned a hole THROUGH my #5 piston in my 12V, and my EGT's almost never see 1200*F+.

Has the head been pulled recently and checked for scoring of the cylinder walls? Or another question I don't think has been asked... Is the head ported?

 

Timing, boost and spray pattern all affect how and where the aluminum melts. For the amount of time the piston actually sees 1200F, short runs going beyond 1200 isn't going to hurt anything. Pulling a grade at 1400F post turbo, on the other hand, could definitely be an issue.

Have you confirmed the water temp with a seperate gauge that is more accurate than the dash? The coolant gauges on both my 98's leave much to be desired. It could be a faulty temp sensor that goes wacko after a certain point. For a turbo, H40 would help, but a prone to breakage if barked. Big wheels and a little shaft don't play well together. You can find budget S300's to work well. I don't know if an HE351W would be worth going to or not on a 12v, they are still fairly tight on the exhaust side. But they can be had cheap.

 

Actually more to point, on most industrial engines, well even yesterday, the engine has pyros per cylinder as well as pre and post turbo. Cylinder temps were around 630°C (1166°F) but the pre turbo temp was 720°C (1328°F). Just because the pre turbo temp is high, doesn't necessarily mean the in cylinder temps are that high. Now this engine is an L7042GSI Waukesha natural gas engine with ALUMINUM pistons running about 4psi boost. It runs like that 24/7 365 and the pistons are fine!

Also, melting a piston can also be more due to (as Tate said) a bad injector spray pattern just as much as high EGT. One hole in a piston is definite indicator of a bad injector, not high EGT.

 

I ran a similar combo for awhile, minus the injectors and I could easily pass 1400 if I wasnt watching the pyro like a hawk.
With my PS62/12 I have enough air that with my foot in it Ive yet to exceed 1300.
You can raise the timing a little to drop egt some, but the big thing is that turbo. Youre out of its map fairly soon and just spinning up hot air.