Forum Discussion
4x4ord wrote:
Your claim that v engines require more cooling capacity than inline engines is confusing me. I might believe that heat management in a V engine is more involved. I can see why a v engine might tend to run a little hotter (which could mean less demand on the cooling system). What exactly do you mean saying a V engine require more cooling. Are you simply meaning that the greater surface area of an inline engine can radiate a little more heat directly into the engine compartment vs a more compact v engine?
It's actually not a claim. It is the truth according the PB/KW/PACCAR engineers and is one of the reasons why engines CAT 3408 or Detroit 8V92 is no longer around in the class 7-8 trucks anymore. The cooling system requirements were greater than the comparable inline 6 engines and added more weight which is a hot commodity on a commercial truck. The other main reason was that it was a fuel hog. As far as the exact or scientific reasons why V engines tend to run hotter, I have am not 100% sure.
I would still check that cap and the system for boost leaks.ShinerBock wrote:
4x4ord wrote:
That is a cool pic. I am not certain how the ECM determines when to defuel to keep your engine from melting down but my suspicion is that your not making 385 hp on a 100 degree day pulling a long steep grade. Shiner can probably set me straight here.
I think safe temperatures are controlled based on things like charge air temp, boost pressure, rpm and the amount of fuel being injected. (Basically EGT can be calculated without being directly measured). So it is likely that defueling occurs based on indirectly measured EGTs. Because the engine defuels on long hard pulls in hot weather the radiator is not being taxed the way it would if the engine was able to put out its full power all the way up the hill. I would be very interested in knowing what it takes to get these trucks to defuel on a long hard pull in 100 degree heat. I think when our pickups defuel it might not be that apparent ...we don’t feel a sudden power loss ... rather the power tapers off. (Im not aware of a time that my pickup defueled but then I’ve never pulled a long steep hill in 100 degree temps)
I’ve never witnessed my Peterbilt defuel on account of EGTs ... The 15 litre engine will put out 550 hp and pull like a freight train until the coolant gets hot. At 220 degrees a red light comes on but there is no reduction in power. I believe it’s 230 degrees where the engine light comes on and the power is suddenly and severely backed off till the coolant drops back down to 220. (It very seldom happens that 230 degrees is reached but 220 is fairly common)
1) There are many variables that cause an engine to defuel, not just EGT's. On a 100F day, he might be closer to 360 hp depending.
2) Not all engine are designed the same and may have different cooling needs especially V engines that generally run hotter and need more cooling capacity than inline designs. Even with two I6 engines, you may have slightly different cooling needs depending on whether it is a closed/semi/open deck design. Diesels generally have a closed deck.
3) When was the last time you replaced or checked the pressure on your radiator cap? If it has been on there for a while and lost it's holding pressure, then it will cause the engine to run hotter under heavy load like that. It is probably a 16 lb cap. Adding 16 lbs of pressure to the system raises the boiling point of water from 212F to 260F. For every 1 lb in pressure that is lost, due to the cap wearing out over time, that boiling point drops by 3F. I would also recommended a boost leak test if you haven't done one in a while. Boost leaks cause higher EGT's which will cause the engine to run hotter under load.
As far as the Pete goes, it never boils. The truck has been in for service and the entire cooling system has been checked out. I actually replaced the thermostats, radiator and even went to the expense of having the water pump removed checked just to be sure. I think the coolant thermostat is 195 degrees, the fan thermostat 210 and warning light 220. They tell me it is working as it should.
Your claim that v engines require more cooling capacity than inline engines is confusing me. I might believe that heat management in a V engine is more involved. I can see why a v engine might tend to run a little hotter (which could mean less demand on the cooling system). What exactly do you mean saying a V engine require more cooling. Are you simply meaning that the greater surface area of an inline engine can radiate a little more heat directly into the engine compartment vs a more compact v engine?4x4ord wrote:
That is a cool pic. I am not certain how the ECM determines when to defuel to keep your engine from melting down but my suspicion is that your not making 385 hp on a 100 degree day pulling a long steep grade. Shiner can probably set me straight here.
I think safe temperatures are controlled based on things like charge air temp, boost pressure, rpm and the amount of fuel being injected. (Basically EGT can be calculated without being directly measured). So it is likely that defueling occurs based on indirectly measured EGTs. Because the engine defuels on long hard pulls in hot weather the radiator is not being taxed the way it would if the engine was able to put out its full power all the way up the hill. I would be very interested in knowing what it takes to get these trucks to defuel on a long hard pull in 100 degree heat. I think when our pickups defuel it might not be that apparent ...we don’t feel a sudden power loss ... rather the power tapers off. (Im not aware of a time that my pickup defueled but then I’ve never pulled a long steep hill in 100 degree temps)
I’ve never witnessed my Peterbilt defuel on account of EGTs ... The 15 litre engine will put out 550 hp and pull like a freight train until the coolant gets hot. At 220 degrees a red light comes on but there is no reduction in power. I believe it’s 230 degrees where the engine light comes on and the power is suddenly and severely backed off till the coolant drops back down to 220. (It very seldom happens that 230 degrees is reached but 220 is fairly common)
1) There are many variables that cause an engine to defuel, not just EGT's. On a 100F day, he might be closer to 360 hp depending.
2) Not all engine are designed the same and may have different cooling needs especially V engines that generally run hotter and need more cooling capacity than inline designs. Even with two I6 engines, you may have slightly different cooling needs depending on whether it is a closed/semi/open deck design. Diesels generally have a closed deck.
3) When was the last time you replaced or checked the pressure on your radiator cap? If it has been on there for a while and lost it's holding pressure, then it will cause the engine to run hotter under heavy load like that. It is probably a 16 lb cap. Adding 16 lbs of pressure to the system raises the boiling point of water from 212F to 260F. For every 1 lb in pressure that is lost, due to the cap wearing out over time, that boiling point drops by 3F. I would also recommended a boost leak test if you haven't done one in a while. Boost leaks cause higher EGT's which will cause the engine to run hotter under load.- Thanks I like the pic also! It was dust and we were just leaving our place in NW WA for SoCal and Texas in the shadows of darkness! Double towing in not ok there or in OR.
I have no clue if it de fuels and most likely it does. Heck I have never noticed it going into re-gen.
Can I maintain 55 on a long 6% grade? Heck NO! But at the top my temps are well within range. Also it safely gets me down those same grades without having to apply my service brakes.
Just turned 80k and still love the truck. Cummins12V98 wrote:
"I mean what’s your opinion about the Cummins that’s 370/850? I’m thinking with 4.10’s that combo will be just awesome for loads under 25k."
My 15 DRW/AISIN is a measly 385/865 and it moves my combined 35k double tow load just fine all across the West Coast. Trans nor engine ever gets hot even in 100 degree weather pulling long 6% grades.
That is a cool pic. I am not certain how the ECM determines when to defuel to keep your engine from melting down but my suspicion is that your not making 385 hp on a 100 degree day pulling a long steep grade. Shiner can probably set me straight here.
I think safe temperatures are controlled based on things like charge air temp, boost pressure, rpm and the amount of fuel being injected. (Basically EGT can be calculated without being directly measured). So it is likely that defueling occurs based on indirectly measured EGTs. Because the engine defuels on long hard pulls in hot weather the radiator is not being taxed the way it would if the engine was able to put out its full power all the way up the hill. I would be very interested in knowing what it takes to get these trucks to defuel on a long hard pull in 100 degree heat. I think when our pickups defuel it might not be that apparent ...we don’t feel a sudden power loss ... rather the power tapers off. (Im not aware of a time that my pickup defueled but then I’ve never pulled a long steep hill in 100 degree temps)
I’ve never witnessed my Peterbilt defuel on account of EGTs ... The 15 litre engine will put out 550 hp and pull like a freight train until the coolant gets hot. At 220 degrees a red light comes on but there is no reduction in power. I believe it’s 230 degrees where the engine light comes on and the power is suddenly and severely backed off till the coolant drops back down to 220. (It very seldom happens that 230 degrees is reached but 220 is fairly common)- Again, I repeat. Edelbrock holds a patent on technology to keep a roller cam follower from turning in the lifter bore and Bosch refused to pay them to use it.
4x4ord wrote:
I don’t blame you, however pump failures are less common in Canada. I think our fuel must provide a little better lubricity. I think I’ll buy what I want based on price and take my chances on the pump. In the unlikely event that my pump fails I’ll hope it’s cornered under warranty,
I think when you're trading trucks every 3-4 years, buy what you want and don't worry about it. I plan on keeping my truck for a very long time so reliability was up near the top of my list of criteria when shopping.- I think, but not sure and I didn’t ask him, but PD Diesel over on YouTube substituted a CP3 in a truck he was experiencing issues with and has experienced no issues. I got the impression that he didn’t do any changes. Just substituted the CP3 for the CP4.2.
I don’t have time to run it down right now but I’m sure one of you can ask him. ShinerBock wrote:
I will say that the Denso HP3 and HP4 pumps are not without their flaws either. We have had some failures on them as well in the Hino(Toyota) medium duty diesel trucks. There are even a few TSB's out for them. The reason why most probably don't here about them is because Denso does not have that big of a market share especially in the personal vehicle market. Even on the commercial side, diesels powered by Denso fuel systems is very small.
I think people need to understand that these pumps are pumping at very high pressures. Just as with horsepower, the higher you go, the likelihood of component failure increases as well. For all you wanting and bragging about more stock short burst power, this is what you get because the manufacturers have to increase pressure every time they have a major power increase in order to stay emissions legal. You can't have your cake and eat it too. As with VG turbos and other components, you are starting to sacrifice reliability for the pursuit of more power on engines that also have to meet emissions.
Hence the reason why I would rather the engine makes have lower power, but use more reliable parts. I can easily add power after the fact that will make the truck more reliable by ditching things like electronically controlled VG turbos and so on that are less reliable than their mechanical counterparts.
It seems as though when they go lower power they use a smaller block and then the same VG turbos and CP 4.2 pumps anyway. I think someone offers a kit to put a CP3 on the new Cummins that doesn't require any tuning. They must do something to the pump to boost the pressure to the identical level that the CP4 is running..... Wouldn't you think Bosch would have gone that route instead of changing to the CP4.2. Even the aftermarket bypass kit that is offered for the Duramax and Ford would put people's minds at ease and seems as though it could be done for a very reasonable cost at the factory. (Aftermarket is expensive but what would it cost Bosch to add something like that to their fuel system ... $30?)Cummins12V98 wrote:
"however pump failures are less common in Canada"
What do you base that on?
I don’t recall ever seeing any actual data on this but have read many times that the failure rate of these pumps is greater in North America vs Europe and significantly higher in the US vs Canada. Basically, I don’t want to worry about having a pump failure so believing the failure rate to be extremely low has worked very well for me. :) I’ve saved a very significant amount of money by purchasing trucks based on price rather than fear of a mechanical problem that should be covered under warranty. But, like I said, I understand someone going to GM over this. I can understand someone avoiding Ford especially, due to Ford’s reputation for refusing warranty.
