In the beginning I never considered the behaviour of the engine temp on my truck was an issue. Yes, on some long hard pulls with the heavy load I have, I would see the temp rise to the 235+ mark, but as soon as we topped the mountain the temps dropped back to the 210 or lower range. During the daily commute in the 110-115 range, stop & go traffic the temp would hug the 210 range. No big deal. Operating as I would expect.

Ok, the last few weeks I have been reading all I can on the overheating issues on the LLY & LB7, mostly for information and comparisons of ideas. Something I read on the LLY thread kinda peaked my interest when someone thought maybe removing the plastic cover in front of the skid plate may have an impact.

I was planning on a trip with friends this past weekend up to NE AZ. This was to be their first trip with a new horsetrailer with living quarters and we wanted to show them the finer points in getting the hell out of Phoenix and spending time in cool weather. Because they have a nice '97 7.3 Powerstroke, I knew this was going to be a slower than normal trip for me, but it was good to 'convoy' and keep an eye on their efforts.

I took the plastic cover off and built a bracket that held the lower radiator hose in the same position as the plastic cover. Within 15 miles pulling the trailer through Gilbert/Mesa heading towards Payson I could see a dramatic difference in the engine temp. The ambient temp was 111 and the engine temp was 2 ticks below 210. (I'll call that 197 for discussion here and 203 for the first tick below 210 marker). As we started to climb the ridges and mountains the engine temp never got past the 203. Granted I was not climbing as fast as I normally would have, but I was impressed. I monitored the transmission temp, and it stayed as it has in the past, no change in its behavoir. We spent a total of 596 miles towing and driving in the mountains and I couldn't keep my eyes off the temp guage (wife was a little cranky about it on a few curves :mad: ).

Ok, the final is this, even though I drove a little slower than normal (in the past I would see temps in the 235+ range) after I took the plastic guard off I never saw my temps rise above 203. Has anybody tried this and seen similar results? If not, is anybody interested it trying this and reporting back?

I have been watching the overheating threads as well. The other thing that interested me was some of the cold air intake work they had done. It would be nice to compile some of the ideas as many of them will apply to LB7 engines.

I wonder whether any of the changes could affect EGT? Could air flow through the engine bay and IAT tempertures have an effect on EGT? I wouldn't sacrifice coolant temps for EGT temps.

Charlie

I missed the suggestion on removing the plastic cover in front of the skid plate. Did the LLY have some data on whether this helped them as well?

Here are some of the areas of change ranked by posters

From Killerbee
1.) sealing (by far, no contest)
2.) nose shroud
3.) CAI (this could rank number 1 or 2 in the extreme tow scenario, not sure)
4.) air dam (no hard data)

From TxChristopher
1)Cold Air
2) Factory air dam ( I would like to see this)
3) Make sure A/C flap is in place.

Like I said in the beginning, my speed was not normal (poor Ford would not have been able to keep up) so I was not able to do a 1 to 1 comparison for the EGTs. That's why I hesitated to mention it. But it seemed as if there was no impact. More later on that.

I have a 04.5 LLY GMC 4x4 CC SB. I have not had a problem with over heating but I thought it would not hurt to do some minor and easily correctable work on the airflow through the areas that should be getting as much air as possible. First I removed the plastic piece that blocked the airflow below the license plate and pulled the plastic piece lower that directs the airflow to the stack. Made a difference of about 5-10 degrees. Tonight I drilled holes in the plastic shield that is in front of the skid plate. I think that someone was talking about doing this. Pictures will show what I did. Holes are 2" on center. The drill bit has a mark on it as a stopping point. Hope this helps others that are having problems with OH.

Carl7264726572667267

Keep us posted on the perforated deflector. That may be the best of all possible worlds. Do you have any particular hills or tow history that you can compare temps vs runs?

A for Annovation!
I love that bit.
You will have to remove a lot more to make a difference, IMO

This reminds me of the swiss cheese air box, one of the dumber lawn dart moves. This probably has more merit, still, I think the splash guard, properly modified, could be a very effective airflow mod. But I would dam the front of it, up to the radiator support, to keep high P from mixing with the low P it provides at the rear. I am working on something like that after taking a few pressure readings all around the guard.

Plus yours is no longer a splash guard. But again, better than some, who only tell other people what to do, referring to some fluids class they took 10 years ago.

Mitchagain,

No hills and no trailer yet. Temp was 98-99 today and the engine ran 205 (always does). The trans was about 140. There is a difference in trans temp but not much. It maybe enough to stop the fan from coming on or the temp from rising on a long pull??? We will see.

Killerbee,

If I noticed enough change I could always drill more holes. I could always fill the holes with electrical box "Goof Plugs". The bit is a step drill. It makes a very clean hole. As for the splashguard. I am more worried about larger objects than splash. From what I heard the 2 wheel drives don't have these anyway only 4x4's.

Carl

PS I did not notice until now that the one picture shows a corner of the stock airflow deflector. I pulled it down to grab more air from the open area near the plate. Might?? make a slight difference.

Mitchagain,

From what I heard the 2 wheel drives don't have these anyway only 4x4's.

.

the 2wd I have seen have them

My truck is an LLY but every truck around here with a plow on it does not have one period they normally take it off when installing snowplow. I reinstalle mine after plow and dont know if it helps or not.

every truck around here with a plow on it does not have one period they normally take it off when installing snowplow.

Just curious why?

While I noted some improvement in stack flow after removing the splash guard, the greatest impact came after sealing the stack and front of the truck. Lots of +P was getting past the stack and into the engine compartment.

The OEM 3" air dam extension's impact is still being assessed. My first tow after doing these mods yielded 2-3mpg improvement towing at 24k lbs GCW, fan only engaged when I stopped and started moving again.

IAT's are still to high, cold air intake should be here next week. This should also help with EGT's. Improving underhood air flow is the biggie right now.

These mods will turn the LB7 into a freakin beast IMHO. That being said drive carefully. JJ

How do you go about sealing the stack and the front of the truck? What all is involved? Also, is there any downside to taking the plastic splash guard near the skid plate off?

Duno if this will help out or not but something I have noticed while plowing, duno if this is helpfull to you guys or not.......

I have NEVER gotten hot plowing. This is with just a juice and a stock trans and stock intake to the current set up. Granted this is durring the winter, air temps are generally around 20* or so but my little thermometer behind the grill says its 120 or so. So I have some heat in the grill area. I have ran with a full grill cover but now just run with the top section of my cloud rider in so I still get air to the trans. The plow itself blocks a ton of air. This wasnt with a winter cover but I have drove down the interstate with air temps in the 50*s and at 75 or so I had no probs, the fan kicked on but I was still ok. I wanted to see what she would run(stock air box, hot juice exhaust) and brought her up to 95 and held a cruise and the temp started to climb, slowed down to 70 and the temp droped like a rock. The plow really throw off some wierd air turbulence tooget wierd flapping noises ect. Temp senso behind the grill says over 100. In plowing trim I am around 9k pounds or so

I very rarely hear the fan kick on.

I did figure out why this happens. On many trucks, the net flow rate of air through the stack does not increase with speed (but your drag and HP requirement sure did). Some truck, especially chevy's, lose radiator flow with speed. I'll skip the tech.

Fingers is a case in point.

Are you sure its a matter of air through the stack? And other factors arent contributing as well? Like I said, my truck never had a problem even with a 1k# 9.5' sail in front of it. Why is a it seem more like an LLY problem?

The only 2 times I have towed they were fairly small loads, one enclosed haulmark with a camero inside going 60MPH and 1 with a dakota on a open trailer(I was driving way faster than I shoulda been :o: most times around 75-80, sometimes faster) Ran normal coolant temps. That was with the air blasting and it being toasty outside. Even stuck in traffic going 5 MPH for awhile on one trip.

The plow screws up air flow so bad that a factory winter cover gets pulled off.

you would not be the first one to say, everything changed at 80 vs 60.

If there is another explanation, I don't know what it would be. A lot of the overheaters like to go fast also, I noticed, maybe coincidence.

It is more of an LLY problem, but IMO that is because the LLY runs closer to it's cooling limits than the LB7. EPA I guess. The cost of lower NOX.

Funny, GM burns it hotter and we just pull the cat. Going nowhere fast for the environmentalists.

so there's 2 more cents. Piggy is getting full.

ratlover, how does this (http://dieselplace.com/forum/showpost.php?p=658798&postcount=786) sound?

80 IIRC was OK....... 85 she started to rise 95 and it started to get outa hand so I backed down(220 IIRC) This was with a blade on.

When I towed I was at 80 and sometimes higher and fine, last time the only reason I towed at 60 and not 65 or so was becasue I had to go rescue a bud that puked his trans on his 1/2 ton towing the trailer, he was keeping up fine at 60 but I didnt want to push it.

I duno if my brief observations help you guy or not? Figured I would post what I saw and see if you guys could use it.

I now have a cowl induction hood(didnt first year of plowing or the first high speed towing or running with the blade) I would like to have acess to what you are using to test air pressure. It would be neat and fun to toy around and try to do something with my intake. Maybe make my cowl functional? Ever since I got my cowl hood I did yank the factory insulation. I just did it becasue it makes the turbo wisle more noticable.

Edit: I guess my whole point behind my observations with the plow is I work my truck pretty hard in the winter and drove it hard in the fall with limited air flow(plow and also winter cover while plowing) and am OK. not saying anyone is right or wrong just giving some experiances I have had. Wish I could help you guys :confused:

the magnehelic can be had for $25 NEW on ebay. I'd recommend a 3" gauge if you plan to use it on the hood, etc.

it have a little lead with a sensor or WTF is it? 25$ sounds doable. magnehelic.....that dosnt sound like a word.....your not sending me on some ebay wild goose chase are ya;)

http://dieselplace.com/forum/attachment.php?attachmentid=6766&d=1122224799

Very easy. search ebay for magnehelic

all you need is some 3/16 id hose. Very sensitive pressure gauge. You will see the cowl hood influence with a little familiarity

How did I get on the LLY forum when it says LB7? Is the forum having problems? Later! Frank

Are you sure its a matter of air through the stack? And other factors arent contributing as well? Like I said, my truck never had a problem even with a 1k# 9.5' sail in front of it. Why is a it seem more like an LLY problem?
actually I think its a problem for all d-max's to some extent. my lb7 gets just as hot as 4 of my friends lly trucks, but we are out west. my observations of all the lly posts and lb7 posts lead me to believe the lb7 gets hot a little slower but gets just as hot(low turbo boost at low rpms) I personally never have a problem until the outside temps hit 95f+. my friend just sealed his stack today and i will be doing mine soon. this seems like the most positive thing that can be done. I always try to remember that previous to the d-max we were not towing heavy loads at 60-70 up 6% grades. anyway my 2 cents.

Somebody want to explain what sealing the stack means? Yes I am dumb.

The stack is the tranny cooler, condensor, intercooler, and radiator. The factory setup is inneficient in that it is not sealed and the leaks cause reduced airflow over these. In an effort to keep the temperature under control, some people have developed a way to get rid of the leaks and make the cooling more efficient.

Somebody want to explain what sealing the stack means? Yes I am dumb.

I did a "Search" for you and found this. (http://dieselplace.com/forum/showthread.php?t=40080)

Your welcome.

Idahofox