Hot day = sluggish CRD

flash7210 · **Posted:** Sun Aug 14, 2011 7:48 am

This has been an on going occurrence since buying my
CRD. I thought it was only my imagination but now I
believe it to be true.
A hot day here in FL = sluggish performance.
Especially on less than 1/4 tank fuel.

It's not really that bad.
It's not dangerously poor performance.
In fact most of the time you probably wouldn't notice.
But when the sun goes down and I've got a fresh full
tank of fuel I definitely notice the improved throttle
response.

papaindigo · **Posted:** Sun Aug 14, 2011 8:05 am

Might try bleeding the fuel filter head. How long has it been since you changed the fuel filter?

Joe Romas · **Posted:** Sun Aug 14, 2011 8:58 am

I think power is reduced when fuel temperature reaches a dangerously high temperature for the CP3 high pressure pump. Your 1/4 tank high temperature example meets that criteria.
But as Papa said it may also be air in the fuel. My CRD originally had a very bad/dangerous what most would discribe as "turbo lag" but lasted much longer expecially when hot. It was air in the fuel and a intank lift pump resolved that issure totally :BANANA:

My worst case was when after filling up on a hot day I needed to turn left onto a busy 55 mph four lane highway. I saw a opening in traffic and pushed the peddal down. It had just enough power to make me a sitting duck. What seemed like forever it regained power. Definetly a dangerous condition. It happened like that often but you never knew when. It was new then and the dealer rubber stamped it "could not duplicate". LOST members identified the problem as air in the fuel and one solution was adding a lift pump. It was found most of the wiring, relay, fuse and logic were all there for a lift pump :JEEPIN:

papaindigo · **Posted:** Sun Aug 14, 2011 9:38 am

I'd be surprised if it's a fuel temp problem as flash7210 is ca 180 miles east of me and we are experiencing the same temp range. I've not had a fuel temp problem since getting a CRD in 2005 nor, as far as I know, has stoutdog in the heat of Tempe, AZ summer. Hence I lean toward a fuel delivery problem that may relate to low fuel levels in the tank somehow.

flash7210 if you go the change the filter route do you have a 2n gen fuel head? If not now is a good time to replace the head and avoid several problems (see http://www.greendieselengineering.com/f ... st/76.page). The new head comes with a new filter and water in the fuel sending unit installed (save your old sending unit just in case as they do fail from time to time). If you are not sure about your fuel head the 2n gen driver side electrical plug should have an obviously spliced in pigtail, a bright blue cover, and be essentially the same size as the passenger side electrical plug. On the 1st gen head the driver side plug is noticeably smaller. Prices on the above site are dated so shop around, as of a month or so back Steve White (http://www.stevewhiteparts.com/) had the best price.

In line or in tank lift pump is a good idea too. I've got but have yet to install an in line pump.

flash7210 · **Posted:** Sun Aug 14, 2011 11:21 am

I have already installed an online lift pump.
Fuel filter was replaced about 6 months ago.
Still original fuel head. No air in fuel.

Like I said this has been on going for 4 years and has
not been any kind of safety issue.

I really think that it's just a hot fuel issue.
Literally it's a day and night difference in performance.

ATXKJ · **Posted:** Sun Aug 14, 2011 1:23 pm

GDE had mentioned the computer would derate the performance if the Fuel gets too hot - however their too hot was ~ 160F fuel temp - and they said they only got that in testing with ~ 2 gallons of fuel left (low fuel light on) while towing 5000 lbs.

so it can - but not very likely.

Sir Sam · **Posted:** Sun Aug 14, 2011 3:59 pm

Could just be a hot day with a hot intercooler, I've noticed the same thing here. Really hot days it feels slow with lots of lag, I think its just a hot intercooler.

My nissan is the same way, but since it has ~300hp its very easy to notice the difference between hot air and cold air. (its a blast to drive it when the temps are around 20 degrees because of the nice cold air getting shoved into the engine.

flash7210 · **Posted:** Sun Aug 14, 2011 6:49 pm

Sam, I think you are right about the hot intercooler.

I'm sure it's just a combination of hot air, hot fuel, hot
everything.
I was just curious if anyone else has noticed this.

warp2diesel · **Posted:** Sun Aug 14, 2011 8:20 pm

Hayden Severe Duty fan clutch, 11 blade V6 Plastic Fan, fuel cooler on return line, no more problems.
OH, remove the Fuel heater relay in the power center.
Having a fuel heater when it is warmer than -10F is as stupid as having heated seats turned on when it is 100F+ and the AC turned off :!:

flash7210 · **Posted:** Sun Aug 14, 2011 8:26 pm

Warp

Where did you mount your fuel cooler?

I keep the fuel heater fuse pulled year round.

warp2diesel · **Posted:** Mon Aug 15, 2011 10:01 am

flash7210 wrote:

Warp

Where did you mount your fuel cooler?

I keep the fuel heater fuse pulled year round.

I will be doing an upgrade when we get the damage to the house we rent out repaired and get it rented. They did not detonate a bomb in the house, but after they moved, they got into the news: http://www.oaoa.com/articles/year-69161-old-son.html
Anyway, I am going to bolt a smaller plate type trans cooler to a larger plate type trans cooler and put them in the same location as the fuel cooler. When I get it done,I will post the pics. Why am I going to replace the existing fuel cooler? It is in the way of where I want to put the large trans cooler and the small cooler will fit on the top. Simple solution, simple is best.

CATCRD · **Posted:** Mon Aug 15, 2011 10:15 pm

I notice much more turbo lag when using the AC in city traffic. The hot condenser makes for a hot intercooler and really extends the turbo lag at takeoff.

Sir Sam · **Posted:** Mon Aug 15, 2011 11:28 pm

CATCRD wrote:

I notice much more turbo lag when using the AC in city traffic. The hot condenser makes for a hot intercooler and really extends the turbo lag at takeoff.

Yup that too, no air flowing over the IC from slow speeds, plus the condenser heat coming off.

I'll deal with it though, I like my AC cold and I don't like it when my.........well I don't like it when parts of my body stick to the other parts of my body.

Glend · **Posted:** Tue Aug 16, 2011 12:13 am

The air flow through the cooling stack (AC condensor/tranny cooler, Intercooler, and Radiator) is very suspect on the CRD. Just sticking the Hayden fan clutch in or putting in the plastic fan is not going to slove the problems caused by air pressure in the engine bay restricting flow through the stack. I have a differential air pressure gauge on the way and I am going to try and document the pressure differences and see exactly what is getting through the stack. A number of KJ CRD owners down here are forming a view that the bonnet (hood to you) needs ventilation (in a low pressure place) to allow the stack to breath better. We shall see.

warp2diesel · **Posted:** Tue Aug 16, 2011 12:25 am

Glend wrote:

The air flow through the cooling stack (AC condensor/tranny cooler, Intercooler, and Radiator) is very suspect on the CRD. Just sticking the Hayden fan clutch in or putting in the plastic fan is not going to slove the problems caused by air pressure in the engine bay restricting flow through the stack. I have a differential air pressure gauge on the way and I am going to try and document the pressure differences and see exactly what is getting through the stack. A number of KJ CRD owners down here are forming a view that the bonnet (hood to you) needs ventilation (in a low pressure place) to allow the stack to breath better. We shall see.

Theory, nice to play with if you have lots of time on your hands.
Reminds me of the arguments against blended wiglets on Aircraft. Bean Counters fought them, but when the REAL ACCOUNTANTS saw the bottom line, the airlines started upgrading their aircraft. Results, more lift, less drag, and 7% fuel savings.
The steel CRD fan is 1940's technology and the stock fan clutch was the cheapest piece of junk the Bean Counters could grab. No wonder it works like crap.
Like I said before, My wife now has me cut back the AC, rarely happened before.
Old Skull reported his EGT dropped faster when he pulled off the road after he towed his 3,000 lb trailer.
Go ahead, run the tests, knock your self out.

flash7210 · **Posted:** Tue Aug 16, 2011 5:49 am

Warp,

How did you route the fuel lines for the fuel cooler?

Joe Romas · **Posted:** Tue Aug 16, 2011 7:25 am

Papa.

We recently took a 2500 mile trip south pulling our 3500# camper and ambient temperatures were in the high ninteties and 100's. I carry an IR thermometor to check tire and brake temperatures.
Since adding a EGT pyrometer when stopping at rest stops I've been making sure the EGT was down to 400 before shutting off the engine :SOMBRERO:

That gave me LOTS of time to check the temperatures of various items and one of them was the fuel filter. I don't recall the exact reading but it was in the 160 range you mention. Everything under the hood was just plain BAKING HOT :frankie:

It rarley required more then half throttle to maintain the speed limit and the various temperatures were supprising. Thermostat temperature was a supprisingly low 176 degrees just like it's supposed to be :shock:

I don't recall the exact fuel filter temperature and fuel level never got below 1/4th tank, but 160 would not supprise me at all. In fact on one particular hill in northern NC on I-77 NB near the Virginia border when the ambient was at or more then 100 power was obviously reduced and full throttle was needed just trying to maintain 65 mph :juggle:

Tire temperatures on the CRD and trailer were a consistant 120 to 125 degrees.

Glend

I too noticed with the "bonnet" raised at rest stops how much air rushed out from BELOW the passanger compartment. But I didn't check how much air rushed out with the hood closed and wonder about airflow while underway. It will be interesting what you find :mrgreen:

Joe

AZ CRD · **Posted:** Tue Aug 16, 2011 9:29 am

Someone mentioned aviation. I suspect that the
change in performance has more to do with what happens to air density as temp increases than what happens with the fuel. Ask any pilot. Thinner air produces less horsepower and less lift. It's a straightforward linear relationship described by the ideal gas law.

Joe Romas · **Posted:** Tue Aug 16, 2011 9:57 am

AZ.

My elevation when I senced fuel was cut could not have been more then 1k above sea level and the hightest I encountered was only 3300 feet. Eastern mountains are not like western mountains :jester:

Turbo chargers eliminate most normal air pressure change related preformance issues caused by elevation changes in engine prefrormance.
On another subject's board, non automotive, humidity is suspected of making a difference and it was very high also.

AZ CRD · **Posted:** Tue Aug 16, 2011 9:37 pm

The turbo as the great equalizer, hmmm? Could be. I'll have to check with my friends who fly turbo Cessnas.

Your relatively low elevation though confirms my point. Driving at low elevation as the summer heats up robs your performance as if you had climbed to 6K, 7K or above--everything else being equal.

Humidity? As far as I know, water vapor does not aid combustion. Maybe you're on to something there. Yet, again, I bet there is an avionics chart somewhere that gives pressure, temperature, altitude, and humidity effects on air density and engine/lift performance.

Hot day = sluggish CRD

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