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Old 06-09-2014, 10:15 AM   #1
Join Date: Aug 2013
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Angry 3208 Cat exhaust temp too high Traveing now

On my 36 ft pusher with 3208 Cat engine, I placed my EGT probe in the exaust mainfold right at one of the exaust ports so it is very close to the actual piston and valves, The exaust them when driving on flat ground is about 800-850 degrees, but even when getting on the freeway it goes up to 1250-1350 degrees, when climbing hills, I allways have to shift down a gear or two just to keep the temps below 1,350, I try to stay at no more than 1,250 but it seems impossible to do. The previos owners must have had a similar problem but never knew it because there was no egt gage. I did turn up throttle adjustment to allow more fuel into the engine and increased the hi rpm just a bit to allow it to shift at a higher rpm. I have seen EGT's as high as 1,450 degrees for short periods of time and it is scares me, I don't want melted pistons, the engine has 38,000 miles which is very low and it never gets hot on the coolant gage or oil temperature gages, I think I located the temp sensor for the egt way too close to the actual exaust gas, maybe it should be located just before the turbo and I need to plug existing hole. I am on the road now on a 2,000 mile trip with lots of climbing and any help would be appreciated, I can move the location pretty easily and would appreciate any thoughts on the issue. Muledeer2

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Old 06-09-2014, 10:20 AM   #2
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I also drive pretty slow, usually 55-59 MPH as I am in no hurry, I climb hills without pushing the rig and usually drop to third or 2nd gear if needed to control temps but they ar still high. climbing in 2nd gear at 20 miles an hour and 1250 degrees with rpm at 2,000.

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Old 06-09-2014, 12:46 PM   #3
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What is the boost pressure?
1999 Trade Winds 7371 Cat 3126B w/current upgrades
1990 D 250 Dodge Ram Cummins Turbo
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Old 06-09-2014, 02:06 PM   #4
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Turning up the fuel will increase power and increase temps. I would look for a less restrictive exhaust system and make sure the air filter in not restricting flow.
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Old 06-09-2014, 08:17 PM   #5
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Probe should be in the down pipe 6" from the turbo flange.
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Old 06-09-2014, 08:21 PM   #6
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if it has a Muffler, I'd swap it out to a straight though muffler.
AND if you still worry about it take some of Your added fuel back out.
(RVM#26) THE U-RV 94 F-700/24 foot U-haul box home built RV
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Old 06-09-2014, 09:02 PM   #7
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FYI I've found backing off the throttle a tad will significantly reduce exhaust temps.
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Old 06-09-2014, 09:52 PM   #8
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Have you talked to Cat to see what kind of exhaust temps you should be seeing? A lot depends on where you are measuring the temps and if Cat says it is OK then. My opinion is that you are to close to the exhaust port for an accurate reading of temps
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Old 06-10-2014, 08:21 AM   #9
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No pressure gage for boost, I have yet to find a good one that is accurate 38 ft. from the turbo. Thanks for the reply
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Old 06-10-2014, 08:23 AM   #10
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No Muffler removed it months ago, straight 4" exaust about 4 feet long from turbo to exit. Also has a new air filter.
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Old 06-10-2014, 08:25 AM   #11
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Yep how far can you back off the throttle and still not get a ticket for going too slow, it's a given that reducing throttle will make it cooler.
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Old 06-10-2014, 08:30 AM   #12
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Should the computer on the cat be "watching" EGT's?

I installed an Isspro "turbocator" on my Mechanical Cummins. My new to me 07 CAT C7 has the on-board computer that regulates EGT's & such.
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Old 06-10-2014, 08:32 AM   #13
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I am thinking it really too close to the valves and piston, the actually probe is lass than 4" from the exaust valve on one of the cylinders, I think it should be moved closer to the turbo inlet to get a reading of all cylinders combined just before the turbo. Measuring just one cylinder so close is not an indication of what happening in the entire engine. muffler is removed and the exaust is less than 4 feet long 4" diameter, and it has a new air filter, the engine is not intercooled, I think an intercooler for air intake would really help.
Thanks for the common sense response. Muledeer2
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Old 06-10-2014, 08:33 AM   #14
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No computer on this model Thanks

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cat, diesel, egt's

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