engine temp on steep grades

Discussion in 'Class A / Diesel Pushers' started by Pillaz, Jun 17, 2008.

  1. Pillaz

    Pillaz Senior Member

    This year I have noticed that on steep grades my engine temp is rising considerably even w/o the boat I normally tow. I drive an older 34' allegro bay w/ 7.4 liter gas engine. I purchased a larger boat this year, tho I have yet to tow it with the mh. Any suggestions on keeping the engine temp down?
     
  2. Guest

    Guest Guest

    RE: engine temp on steep grades

    first ,, welcome to the forum,,, is u'r rv new to u ,, or did u buy it new ,, the reason i'm asking ,, if u didn't buy it new ,, then some of the amint may have been neglected ,, but i'm not going into that right ,, now ,,, how much does u'r temp increase on pulls ,, most increase are normal ,, due to the weight (of just the MH) ,, then u factor in toads (or towing vehicles ,, even boats) then that wieght goes up more ,, but too really help u out ,, we need to know how much the temp goes up ,, and what type of hills u are pulling ,, when the temp goes up ,, then we can go from there on advice :approve: ;) :) :)
     
  3. C Nash

    C Nash Senior Member

    Re: engine temp on steep grades

    Like 730 said we need more info. What year and how many miles? Do you hear the fan kick in when the temp goes up? Are the outside temp the same as you are compairing it to? Welcome to the forum :)
     
  4. Pillaz

    Pillaz Senior Member

    RE: engine temp on steep grades

    First let me say thanks for the response. I have had the mh three yrs. It is a 91' with 52k on it. I live in the Catskill mtns of NY. The temp gage gets darn close to the red, in above 90 degree outside temps on long hills. Ya know the ones where they add an extra right lane for trucks. I expect the engine temp to rise in these conditions. But when the temp gage gets close to the red I get nervous. The fan on radiator does kick on. Regular service is always done. I switched from 10-40 oil to 20-50 oil for the last oil change thinking that this might help. I do have some trip planned that involve towing a 5k lbs boat. I am afraid that if the outside temp is above 90 I am going to be in trouble.
    One other thing, the previous owner replaced the 4 barrell carb with a 2 barrel carb. Why, I don't know so I am wondering if that is not part of the problem.
     
  5. elkhartjim

    elkhartjim Senior Member

    Re: engine temp on steep grades

    Have you tried down shifting to get more rpm's to see if that helps? Have you changed the coolant and flushed the radiator recently? Are you running the engine ac when this is happening? Just my thoughts. Good luck and please let us know how you resolve this.
     
  6. C Nash

    C Nash Senior Member

    Re: engine temp on steep grades

    Could be a defected guage or sending unit. Check the radiator for bugs and trash in the fin area. The clutch on the fan could also be going bad. If flushing as Jim suggested does no good might be time to replace or have the radiator rodded out. Don't go for the boil out waste of time IMO. Have you lost some power? partial restriced exhaust can cause the engine to heat more than normal. I can't believe someone put a two barrel carb on it. Are you sure this engine does not have center fuel injection? Model year and changes tend to run together on me now.
     
  7. Kirk

    Kirk Senior Member

    Re: engine temp on steep grades

    Before you start towing that boat, let me suggest that you check the hitch on the Allegro. The one that I owned had a hitch that was only rated for 3500#. I would bet that with 5K# of boat you are going to be very over-loaded. You sure want all of the cooling you can get.

    On a 91 with a 454 you have the P-30 chassis and it had a GVWR of 16K and I think the GCWR was only about 19K.
     
  8. Pillaz

    Pillaz Senior Member

    RE: engine temp on steep grades

    Thanks for all of the advise. I read the manual over the weekend and it states that long steep inclines will raise engine temp and that I should downshift. So that is what I am going to do. I also gently presure washed the radiator. I am also going to change the coolant to be on the safe side. We are going to Lake Champlain July 4th weekend with the boat so i will let you know how I made out.
     
  9. Paul235

    Paul235 New Member

    RE: engine temp on steep grades

    You will get some of the best RV/MH info and advice with this group anywhere on the web. I haven't seen the subject of transmission heat and the associated cooler(s) mentioned that might be contributing to the problem. Tranny cooling is often tied into the radiator as well as having a separate cooler or coolers. Check that the coolant used is at the proper mix ratio with water. More than a 50/50 mix will not transfer heat as well and increase overall temps. I also question why the 4 barrell carb was replaced. Doesn't seem like a logical step in improving any performance or MPG issues.
     
  10. C Nash

    C Nash Senior Member

    Re: engine temp on steep grades

    Really think he might have the throttle body instead of a carb but time has faded my memory on when the change to throttle body took place.
     
  11. H2H1

    H2H1 Senior Member

    Re: engine temp on steep grades

    How about changing the thermostat, if it is that old then I would think the stat is bad and not opening all the way up. But there again I am not a mechanic, but use to have to work on my old cars and trucks.
     
  12. Pillaz

    Pillaz Senior Member

    Re: engine temp on steep grades

    Trust me no throttle body. Its a carb. Thanks for all of the advise.
     
  13. C Nash

    C Nash Senior Member

    Re: engine temp on steep grades

    If it's a carb you could be getting into a lean condition which is bad on internal engine parts.
     
  14. C Nash

    C Nash Senior Member

    Re: engine temp on steep grades

    Is the carb computer controled? If not the timing could be a problem. Also if no computer the vac advance and HEI centrifucal advance needs checking.
     
  15. Shorty

    Shorty Senior Member

    Re: engine temp on steep grades

    Had the same problem when my clutch fan on the 454 started to go. Had an electric fan also.
    Ended up replacing the fan...twice
    found out that it was not a heavy duty fan...but a seveir duty clutch fan
    Pain in the butt too, laying over the top of the engine and changing it from inside the coach
     
  16. Pillaz

    Pillaz Senior Member

    Re: engine temp on steep grades

    Thanks Nash. I am beginning to think the carb is running a little rich. We went to Lake Champlain last weekend. On the Way there Temps where in the mid 70s and we cruised at 70mph and no problems. On the way back temps were in the high 80's Toward the end of our trip the engine temp started to raise. The heavy boat seemed to have little effect on the engine temp. I have to say I have gotten some great advice on this forum.
    Thanks to all who responded.
     
  17. C Nash

    C Nash Senior Member

    Re: engine temp on steep grades

    Hard to believe a 2 barrel would be running rich unless someone has installed some very big jets in it. Is it a rochester? How hot does it run? Have you ever heard a gurgling sound when you shut the engine down. The temp will normally rise even more when first shut down. I still would suppect the fan clutch. Might want to look into installing a electric fan. As someone mention the AC will also increase the temp. Ac pressure could be high and creat more heat in the ac condenser core. Might also want to have the engine checked for head gaskets and cracks. Keep us posted.
     
  18. Pillaz

    Pillaz Senior Member

    Re: engine temp on steep grades

    It has an electric fan as well which does work. No gurgling sounds when it engine is turned off. You may be right that it is a fan clutch. a/c is always off. In fact I ran the heat in an attempt to keep engine temps down. It is not loosing oil nor is there water in the oil or any funny sounds or smoke comming from the engine. It seems to run fine. The only time the temp rises is on stepp grades on hot days.
     
  19. H2H1

    H2H1 Senior Member

    Re: engine temp on steep grades

    Jim have you changed out your thermostat? Try this and see if this helps. I had an old truck that would run hot when pulling a trailer loaded with a tractor. I changed the thermostat and solve the heating problem. I know this might not be your problem, but it can't hurt. :laugh: :cool:
     
  20. C Nash

    C Nash Senior Member

    Re: engine temp on steep grades

    If it is not computer controled I would also go to a degree colder thermostate. I would still like to know what kind of 2 barrell card is on the motor? Rodchester, carter, holley? It does seem to ring a bell that some of the older chevy trucks 454s had a 2 barrell.
     

Share This Page