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Crankcase Concerns, EGT Troubles & Clutch Choices - Top Diesel Tech Questions

You've Got Questions? We've Got Answers!

Jason Sands
Jun 4, 2015
Photographers: Jason Sands
Crankcase Concerns
My Ford pickup truck has a 6.4L Ford Power Stroke diesel engine, as well as an H&S Mini Maxx programmer, an S&B intake, and aftermarket exhaust. I was looking into buying a crankcase ventilation kit to relieve crankcase pressure, but I don't really know much about it. Just looking for some advice on whether I need one or not.
Ted Young
Via email
Photo 2/4   |   Some engine blow-by on diesels is common, although excessive smoke or oil coming out of a draft tube can be a bad sign and can potentially signal problems like a bad injector or worn-out engine.
We're glad you asked, because crankcase ventilation isn't commonly discussed, although it is a subject diesel owners should be aware of. In a running engine of any sort—diesel or not—ring sealing isn't perfect, and a small amount of combustion pressure will get by the piston rings and into the crankcase. It’s important to understand that the crankcase is a pretty large area. It holds the rods, crankshaft, oil pan, and basically every passage that oil travels through in the engine.
Any crankcase pressure really isn't a good thing, as it taxes most of the gaskets that try to keep oil in the engine. Without proper ventilation, the gaskets are tasked with sealing oil, as well as crankcase pressure.
However, that's not the only downside. Stock ventilating systems on most newer engines resend any blow-by directly back into the intake tract, instead of just venting it to atmosphere (as it was with older diesels). This means that over time, a lot of oil residue builds up in the entire intake tract. The excess oil is especially hard on intercooler boots, which can blow off under hard acceleration and high boost when coated with oil.
Crankcase pressure becomes an issue mostly as boost rises to very high levels, like 60 psi or more. Since the 6.4Ls were designed to make 40 psi from the factory, you don't really need a crankcase vent like other higher-boost engines.
EGT Troubles
I need some advice to address my EGT issue. I have an ’02 Cummins-powered Ram with a 5-inch straight exhaust, a Scottie 2 intake that sucks air from the fender and the cowl, a MADS Smarty programmer, an Industrial Injection Hot Rod VP44 injection pump, a FASS 150-gph lift pump, a Banks Power 3.5-inch intake manifold, a three-piece exhaust manifold, an HTT Street Stock 62/65/14 turbo, and injectors that are rated between 90 and 120 hp. The injectors were put in there before I bought it. I've been told which ones they are, but I can't remember exactly, to be honest.
Here's my problem. I tow a 19-foot jet boat during the summer and a fullsize K5 Blazer on 37s to the dunes. My EGT is pretty high—even on flat ground on the highway. It stays between 950 and 1,100 degrees completely empty at 70 to 75 mph on flat ground. When I hit even a slight grade or overpass unloaded, it easily climbs beyond 1,200 degrees. When I hook up something light like the boat, I easily exceed 1,200 degrees even when I kick it out of overdrive and back off the throttle.
I see 6 to 9 psi of boost unloaded and between 8 psi on flat ground and 20 psi uphill with it kicked out of overdrive. I have backed off the tuners and even turned them completely off—and I pulled the aftermarket injectors and put the factory ones back in. All three things netted an increase in EGT, or at least made it climb even faster. I don't care about increasing the power since it dyno'd at 433 hp and 1,005 lb-ft, which is plenty to make my pig pass up imports all day long. I simply want to be able to tow my truck and boat without having to back off the throttle so much that kids can pedal their bicycles faster than me.
It's hard to find good advice about this problem. Most people say to cut back the Smarty and TST, but I've done that and it’s only made things worse. I always turn the TST box off when I tow, and it always seems to run the best and coolest with the Smarty on a level with added timing. Any advice or help would be appreciated more than you know!
Stu Sherman
-via email
Photo 3/4   |   We suspect that 99.9 percent of exhaust gas temperature (EGT) gauges out there are accurate, but there are some that might not be. A good way to test a gauge is to let a diesel idle after driving it around. After about 30 seconds to one minute, nearly all diesels will measure about 350 to 400 degrees pre-turbo, in gear. Anything way above or below that, and you might be looking at a gauge or probe issue.
It's not too often that we get a tech question that just makes us say, "Huh?!" but this is definitely one of them. In theory, your combination of turbo, pump, and injector should work, as we've seen VP-equipped trucks with 350hp injectors cruise at highway speeds without an issue. If your question is about 1,200-degree EGT while towing, we'd lecture you about keeping boost and rpm up and dropping down a gear. But you've already tried that, which again leads us to the aforementioned "Huh?!"
Cruising exhaust gas temperature should be about 600 to 800 degrees, which is way cooler than the 950 to 1,100 degrees you're seeing. Now, there are a few unknown factors such as tire size (huge 44- to 48-inch tires can promote the type of EGT you described), but we're assuming your truck is pretty much normal tire-wise, since you didn’t mention it.
While you're going to get a lot of suggestions like water injection or a larger turbine, it's our guess that there is a greater problem that still needs to be addressed. One thing you didn't mention is whether you've tried a different EGT gauge or probe. While it's rare, we have seen EGT gauges that are off by a good margin. Some have read high, others low.
One GM truck owner we ran into was bragging about how he could tow a trailer with his programmer on Level 5, with the Duramax’s EGT never exceeding 1,000 degrees. It sounded fishy, so we looked into it, and cruising speeds registered a way-low 400 degrees, and the pyro would go all the way down to 200 degrees (normal pre-turbo is 400 or so) after idling for 30 seconds before the truck was shut off. We quickly surmised that the truck wasn't actually towing at 1,000 degrees and the actual EGT was a lot hotter.
So, the first thing we'd try is a new gauge or pyro probe, but that still may not fix it. There is a chance your EGT issues are real, which leads us to our second theory—your engine’s timing is way off. You mentioned dyno numbers of 433 hp/1,005 lb-ft, which sounds about 50hp low and 50-lb-ft high. If the truck has its timing retarded too far, all that extra exhaust energy creates boost and spools the turbo sooner, which can lead to a big torque number. The lack of timing, however, will be evident in the peak power, which will be low, just as it is in your case. You also don't mention your truck’s fuel mileage. If the timing is off, mileage will usually suffer.
The good news here is, if your timing is off, there is a way you can check it with a pulse-style timing light attachment that clamps to an injection line and senses when the line is under pressure. These gizmos are usually very accurate and should tell you actual timing within a few degrees. Since they're not cheap and properly checking timing involves finding the engine’s top dead center very precisely, we'd probably let a shop do it.
Single or Multi-Disc Clutch?
I was fortunate enough to come across a ’98½ Dodge Ram 2500 with a manual five-speed transmission, 140,000 miles, newly replaced injectors, and a new fuel pump. The previous owner towed a fifth-wheel and added an Edge programmer, exhaust brake, turbo-back 4-inch exhaust, and K&N air filter.
I suspect my clutch will need to be replaced shortly, as every time I accelerate hard, the engine revs up, but my speed doesn't respond at the same rate. I suspect slippage, but I don't know how to go about selecting a new one. I do some towing and hauling and I don't plan on making any major engine modifications to boost my power, but I'm still a little confused about whether to get a single-disc or dual-disc unit. Any advice would be great.
Josh Reed
Edmonds, Washington
Photo 4/4   |   Manual-transmission trucks are becoming less and less common, but there are still plenty of them out there. For most folks, a single-disc clutch will do the job, but those who want to sled pull or drag race should look into a dual- or triple-disc clutch to prevent slippage.
Choosing a clutch can be rather tricky, but since your power levels are going to stay the same, it's a little simpler. While power is often used to rate clutches, it's actually torque that causes everything to slip, which is why Formula 1 cars can make 900 hp—at 12,000 rpm—with clutches the size of dinner plates. Diesels, on the other hand, are just the opposite. They make good power down low, which requires large-diameter clutches with a lot of clutch material and clamping force.
When it comes to choosing a clutch for a street truck, it basically comes down to buying a single-disc clutch, or a double- or triple-disc upgrade. Single-disc clutches drive differently than multi-disc units, and there is a lot more give or slip in the engagement than multi-disc units. Especially when backing up, the double- and triple-disc clutches have a tendency to chatter (or grab and then slip in quick succession) when engaging. Pedal pressure is also much higher than stock, as the extra force is needed to resist big torque levels. It makes no difference whether it's a Ford, Dodge, or GM truck with a stick shift; these attributes pretty much hold true for any brand.
In most cases, if the truck's owner is planning to stay in the 300 to 500hp range (along with 500 to 900 lb-ft of torque), a single-disc clutch can be used to maintain stock-like driving manners and increase holding capacity over the factory version. Since it sounds like you're looking for reliability more than anything, a nice single-disc will be all you need.



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