Chevy 454 P-30 engine cooling question

[kattkisson]

I have a 92 Winnebago with 454.  It has a fan clutch for the engine fan and a single large electric fan in front of everything. 


I went to the mountains this past weekend and the temp. started doing funny things right out of the gate.  Temp went higher than normal and stayed there long enough for me to consider turning around and coming back home. Then it started swinging thru a 25 deg range.  When I had to climb the mountain it remained rock steady around 210 which I think is very good.  Coming back from the mountains the gauge showed in the 155 range which to happen by my understanding would require the thermostat to be stuck open.(It is a 195 deg. unit)


Today I replace the thermostat and the fan clutch.  I drilled the thermostat since the factory didn't in case I was getting air into the system somewhere and keeping the thermostat from reacting. I cleaned the connectors for the two temp sensors on the heads.


My questions  1.  Is the electric fan supposed to come on more or less "first" before the clutch locks up?I thought up to today that the electric fan was for only when the A-C was on but that is not the case at present. 


2.  Where could the switch be for the fan?  I don't see it in the hoses or the Radiator tanks. 


Thanks

[Rickf1985]

On mine there is a sensor on the lower left of the radiator. Mine is on a switch right now since the wiring and relays were all cut up and I have not had time to straighten it all out. The new aluminum radiator did not have a spot for it but I am sure I could find a place that would work just as well.

[kattkisson]

I am a great believer on passing on info as it is discovered so here goes.

Each head on my engine has an electric device screwed into it on the manifold side center.  Though they look the same and were assumed to be separate temp sensors for the gauge that is not the case.  The one on the right(alternator side) is a thermo switch that is supposed to cut on at 225F.  Don't know when it drops out.  This is used to cut on the fan relay.  The one on the left is a variable thermistor for the gauge. 

So either I have a flow problem thru the head or the switch is cutting on way to early.  Don't know how I will pursue this yet.

[CJ7365]

I have  95 Winn Brave 454


My electric fan turns on before the clutch fan, in fact my temp only rises above 210 going up a grade, and looks like the clutch fan turns on around 220

[kattkisson]

Further info.
After much research I found the following:

Fan switch which threads into head   NAPA Echlin FS104  1/2" MPT
Sending unit for Temp Switch that threads into other head  NAPA Echlin TS4019  3/8" MPT  This may or may not require a threaded bushing--I haven't installed it yet.

I was able to get both for $38.

[TripleJ]

Personally, Id rather have the fans turn on even before the thermostat opens.  I cant think of an instance where too much airflow is a problem, but too little airflow is always a problem.

I went all electric, and my fans can blow all day long for all I care.  Its the thermostat that actually regulates the engine temperature

[ClydesdaleKevin]

I added a switch on my dash, fused and using a solenoid, so that I can turn on the electric fans when I am climbing hills, and see the temp gauges going up...I always watch my gauges.  I also added an additional fan with an additional transmission cooler, since we ride heavy and tow heavy.

That said, while my average operating temps are around 185 for the water and right around 110 for the transmission, climbing steep hills can bring the water temp as high as 220, and the trans temp as high as 150...which are both still safe operating ranges.  I have noticed both temps dropping below thermostat ranges on long down hills in cool weather, and its nothing to worry about.

As long as you aren't getting much hotter than this, don't worry too much about it.

Kev

[kattkisson]

Hello everyone-
I am still having the cooling system temps do funny things if anybody has any ideas.  For the life of me it acts like one of the heads needs to Burp but I have done everything I know to do.


When I start out from cold the temp rise is up to 225.  This is at a constant 55-60 mph.  After some time it will drop down to 185-195 and then cycle back up to 225 a couple of times .  Then if I'm lucky it will level out at about 195 after 100 miles.


I have replaced the Thermostat and drilled an air hole in it.  I have replaced the fan clutch and the temp sensor for the gauge and the fan switch. Both fans function as they should.  Coolant is rising and falling in the bottle as it should and I'm not loosing any. Temps have largely been confirmed by a hand held temp reader.


Getting ready to head down to Gatlingburg,Tenn -Asheville in the mountains and am getting spooked.  Any Ideas?

[jeno]

I wonder if there could be air in the system?

[Rickf1985]

Have you ever replaced the head gaskets? It is possible that the wrong gaskets were used. If the rise in temps corresponds with load then it could also be a partially blown head gasket. Have it checked for hydrocarbons in the cooling system.

[kattkisson]

haven't replaced the head gaskets and the temp rise does not seem to be related to load .  In fact in the mountains it seems to level out about 195-200. 

i'm fishing as to whether there are some bleed ports on the heads somewhere I know nothing about.  As I stated it acts to me like it needs to burp and somehow can't.

[Rickf1985]

That is why I asked about the head gaskets, There are early and late style gaskets and they are not interchangeable. Someone actually just put the technical bulletins up on here not long ago ant that issue is addressed in one of the bulletins.
Found them, they are actually only a couple posts down but here is a link to the PDF.

http://blackhillslaserdesigns.com/uploads/3/1/8/7/3187069/aera_technical_bulletins_454engine.pdf

[kattkisson]

I recently returned from a 1k mile trip and am still having cooling problems.  I am convinced that I have a sticking thermostat.  Electric fan and fan clutch are working as needed with the electric one running all the time after warmup. Temp will be fine for hundreds of miles then start treading upward .  At times it will read in the near cold range.


I want to replace the thermostat once more.  I have been using a Napa #531090 which is made be Stant and rated at 195F opening  This thermostat uses a ring gasket . I understand from the people I have talked to that this is a b-stardo style thermostat in the big block.  Others listed for the 1992 big block are larger and use a gasket instead of the ring.


Where I need help --does anyone have anybody's else's Part #'s for a high flow or standard thermostat for that matter that fits this 454.  It's time to try another make.

[DaveVA78Chieftain]

GM P/N 24577299

Crosses to NAPA P/N THM 215

[kattkisson]

Thanks.  THM 215 is the "Regular" series.  The THM531090 is the" Premium" Series of the same thing.  I just want to try someones else's thermostat such as Mr.Gasket or other as I have tried 2 of the former with the same results. Anybody have any recommendations?

[Rickf1985]

Not telling you not to try or to discourage you but they are all built the same way and all open the same amount. That is limited by the space available in the housing. The older style is larger in diameter on the outer ring but I am pretty sure you are going to find the opening is the same size. Also check to be sure it will seal in your housing, the o-ring style and the gasket style usually use different housings.

[cncsparky]

Have you done any tune up on the engine?  Checked timing?  Retarded timing can cause it to run hot also.

[kattkisson]

Thanks for all comments.  Timing is 4deg.BTDC.  I would pursue this further if it did not run at normal temp for long periods under differing conditions. It just goes on a bender every so often which I have in my head should be the thermostat especially since it runs cold at times

[Elandan2]

Have you compared the wind outside while you are driving with the engine temperature?  I have noticed with ours that if I am driving into the wind (seems like about 95% of the time  Hm? ) that the engine temperature is lower than if I am driving with the wind.  Just wondering if that may be what you are experiencing.  Rick

[kattkisson]

thanks Rick.  Will notice this going forward and see if there is a relationship.

[kattkisson]

Does Transmission fluid circulate all the time through the transmission cooler build into the radiator or just when something tells it to? This may be related.

[DaveVA78Chieftain]

circulates all the time