Join Date: Jul 2008
Location: Folsom CA
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1997 Ford 7.3L very high EGT Question
My good buddy and a great guy has been worked over pretty much by two shops now. He called and came by last night looking for help.
1997 PSD, DI engine 7.3L. 4x4 quad cab F350 Automatic.
He was told by a Diesel shop that he needs a new engine that one cyl is down to 350 psi and the engine is going to break.
I know a little about these engines and this one sounds great. He did have a bad number 4 injector and that is the low cyl, 350 psi. I don't know what perfect compression is on the 7.3L.
This thing runs great, starts great I had him take me for a ride up a local long hill at 65 mph. It pulled very strong but the egt gauge went quickly up, almost as fast as he pushed his foot down. I also noted only 12 psi of boost at 2000 RPM under half throttle or less. Never saw more than 12 but I don't know how hard he pushed the pedal. Around town I never saw more than 6 lbs of boost in very easy driving. He is very concerned he will burn up his engine. He also reports that on a hunting trip crossing Nevada he could not run 70 MPH with his camper on top because the EGT kept pushing past the orange into the red. This is a full camper, maybe 3,000 pounds but a fair amount of wind block. Not much load for a good running 7.3L.
This truck has 165,000 miles.
I think the bad injector since replaced may have contributed by washing the cyl down before it was replaced and damaged piston rings.
The engine sounds too good and pulls so nice I suspect even if the cyl is down on compression that this engine is still at 90%+ capacity and may last another 100,000.
It burns no oil. Water temp is perfect and stays planted at the gauge center.
Can I ask if anyone knows the cause of rapid EGT heat. It jumps as soon as the throttle goes down and keeps climbing.
A new down pipe was just welded in prior to the high egt issues. He also said the shop modified his computer while it was in. Looking at the new down pipe is appears to be poorly installed, there is barely 1/16 of an inch clearance between the tranny, tranny coolant lines and the down pipe. It appears to me to be 3". Tranny temp has been running around 160 with an oversize cooler installed.
I know this is limited information but I really would like to assist. He is a young man with three young children to raise and extra money is hard to come by. So far he has spent close to $ 3,000. and the EGT still climbs quickly. I wonder if it is a bad EGT sensor. The EGT sensor was installed prior to the new down pipe and worked normally before. This guy does not turn his own wrenches so everything has been done in shops so far.
I do not note any unusual diesel clatter at idle so it sounds like the timing is very close if not stock.
On the hunting trip my buddy was sleeping and his 82 year old hunting partner was driving, my buddy awoke to a loud engine noise that really scared him. When he looked at the gauges the pyrometer was in the red and they were traveling 75mph. He was only asleep 15 minutes when the noise woke him. Once cooled down the engine started and ran normally. Could this have been the waste gate blowing off pressure, an exhaust leak opened by the heat?
The engine sounds and runs too good to have internal damage.
No sign of water leak so I think head gaskets are good. I am leaning towards false readings on the EGT but I hope to pick up some informed opinions here.
Thanks a lot.