# engine temp on steep grades



## Pillaz (Jun 17, 2008)

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?


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## Guest (Jun 17, 2008)

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:


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## C Nash (Jun 18, 2008)

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


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## Pillaz (Jun 21, 2008)

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.


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## elkhartjim (Jun 21, 2008)

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.


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## C Nash (Jun 21, 2008)

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.


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## Kirk (Jun 21, 2008)

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.


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## Pillaz (Jun 23, 2008)

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.


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## Paul235 (Jun 24, 2008)

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.


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## C Nash (Jun 24, 2008)

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.


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## H2H1 (Jun 24, 2008)

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.


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## Pillaz (Jun 30, 2008)

Re: engine temp on steep grades

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


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## C Nash (Jun 30, 2008)

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.


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## C Nash (Jun 30, 2008)

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.


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## Shorty (Jun 30, 2008)

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


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## Pillaz (Jul 9, 2008)

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.


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## C Nash (Jul 9, 2008)

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.


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## Pillaz (Jul 10, 2008)

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.


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## H2H1 (Jul 10, 2008)

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:


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## C Nash (Jul 10, 2008)

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.


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## Pillaz (Jul 11, 2008)

Re: engine temp on steep grades

I know that it left the factory with a 4 barrell carb. The previous owner put a 2 barrel on it.  I am going to check out the fan clutch this weekend when I get a second and I will let you know about the carb and how I made out on monday. I don't believe they put two barrel carbs on a 454 since the 70's This engine was manufactured in 1990. Last year I thought about putting a 4 barrel back on it, of coarse this would mean a new intake manifold as well. I also thought about putting a stainless steal high flow exhaust with headers on it which would give it much better horse power and better fuel ecconomy. But it is hard to put a lot of $ into a MH I only paid $8k for.
Again guys, Thanks for all of the advise!


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## C Nash (Jul 11, 2008)

Re: engine temp on steep grades

Go with the aluminum intake and get the headers.  I still like the 4 barrell Rodchester Q-jet carbs for all around performance and mpg. Holley for high performance. Nothing wrong with putting some $$ in when you only have that kind of money in a MH. Best way to go.


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## Pillaz (Jul 16, 2008)

Re: engine temp on steep grades

I am not having much luck. I have changed the fan clutch(sevier duty) and Thermostat with a cooler one. (it had a 195 and I put a 180 on it) I think the carb is running rich. Even though it presumably has smaller jets it also restricts air flow.) I am going to pull a couple of spark plugs today when I get home from work and check them out. If they are not fowled then its not the carb and I am at a complete loss. It would seem to me that if it were running that rich or lean for that matter that it would run rough or stall which it does not. It runs at normal temp around town. I think I have spent a ton of $ on gas running it back and forth to a hill on a highway. It seems that weight has no effect as my test runs have been done when the MH is largely empty.


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## Guest (Jul 16, 2008)

Re: engine temp on steep grades

can i ask this ,, does it still have the cat converter on it ??? if so it might be getting plugged ,, but the spark plugs will tell u that ,, if they are black,, it's over fueling ,, or can't breath ,, or should i say exhale ...


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## Pillaz (Jul 17, 2008)

Re: engine temp on steep grades

Thanks to all for the advice. The plugs were not fowled at least not badly. I flushed the radiator with fresh water and then refilled with a 50/50 mix of coolant. Low and behold it seems to have made a difference. On hindsight it was probably the first thing I should have done.
  I still think it needs a 4 barrel carb and headers on it. Which I will probably do when I get time for a big prodgect. 
Oh and by the way Nash. The carb is electronically control and says PEI on it. I'm not sure what that means
  Thanks especailly to C Nash and 730 for all of the input. If any of you guys make it up to central NY I will buy you a drink!


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