4.2l 93 R.R.C (lwb) overheating

[extremrovers]

NEW...Water pump, Timing chain, Expansion cap, Thermostat, Heater core, and replaced all hoses and belts .... Fan and radiator appear to be in good working condition..
And its overheating?!? If left to idle, even for an Hour it dose not overheat.... But if I drive it for about 15miles it over heats ....and when the temperature gage gets to red No Check Engine Light comes on ..... I also noticed the upper hose going from the radiator to the thermostat starts to expend and gets hard (something like a balloon).

All help is Appreciated.

[TerryS]

The hard, expanding top hose is the giveaway. Go down the RRC threads and read entirely the one a few days ago on coolant loss/overheating.

Go out, take the little black cap off the radiator, start the car, let it warm up a bit, a look inside the radiator while reving the engine. Are you seeing a rush of tiny bubbles (probably flowing from your right to left)
The top hose is expanding because you're building high system pressures. You're overheating because these pressures have lifted the relief cap and blown out the coolant . To confirm that sequence, you can take a milk jug, tie it in somewhere, with the expansion tank overflow hose into it, and drive down the highway (not a quiet country rd, but then, is there such a thing in FL?) and when you gage starts creeping up STOP and see how much coolant has gone from the system into the milk jug.

Coolant loss before overheating, is the result of high combustion pressure getting into the low (15-20 psi) cooling system. The route these pressures are traveling are (A) a crack in the head somewhere between the combustion chamber and cooling passages. Cracks are occassionally found in the exhaust valve pocket. They wont be in the intake pocket and this isn't a pressure area anyway. Evidence of a crack in this area can show up as an unusual amout of 'steam' or water vapor out the tail pipe. The next possible source (B) is a blown headgasket, but this is less likely because the gasket would have to blow from one of the 4 corner cylinders out towards either the forward or rear end of the engine (as oppose to out sideways) because these are the locations of the water passageway between block and head. The third (C) and most likely is a cylinder liner becoming loose between itself and the aluminum block. This is the greatest likelyhood.

[extremrovers]

I don't lose any coolant ..?? NO coolant LEAKS and the engine dose not lose any power it runs Great.

[TerryS]

I'd be very concerned about the fact that the top hose is getting very hard, to the point of expanding (If it's a newish hose then you can easily ruture the palstic expansion tank). But, if you're sure you're not loosing coolant, and you have confirmed that you are overheating, and not just a gage problem (notoriuously unreliable) Then you may have a sticky thermostat. Sticks closed, restricts flow, gets hot (the hotter, the greater the pressure) and top hose swells. If that's all it is, and it's easy enough to just change out thethermostat for a new one, then count your blessings. Be sure you get the thermostat installed in the right direction, with the air vent to the top. I didn't ask earlier, and I guess you've checked, but is your viscous fan clutch working?

[extremrovers]

thermostat is new 91c and its in the right way ..and the fan looks OK I DRIVE FOR ABOUT 15 MILES THE THE GAGE SHOWS HOT IF I STOP AND LET THE (( CAR )) TO COOL DOWN FOR ABOUT 5 MIN THEN THE GAGE IS AT NORMAL TEMP (HALF WAY) THE TOP HOSE IS VERY HARD AND EXPENDING ....... I WILL TRY TO TAKE OUT THE TREMOSTAT SEE IF IT HELPS...I AM NOT LOOSING COOLANT VISCOUS FAN CLUTCH OK AND THE ENGINE RUNS GREAT...??? I DON'T KNOW WHAT ELSE TO DO..?? THANK YOU FOR ALL YOUR HELP !!!!

[TerryS]

91C is a little hotter than I would run, which is 88C(190F)
Is your timing OK ? about 8 degrees BTDC, at idle. To far advanced makes lots of power, but lots of heat. Too far retarded makes lots of heat out the manifolds, luggy power. Is your fan actually going into lockup when the engine gets that hot, or is it just coasting? If the clutch is original, it's almost surely dead, but even new ones don't go much more than 3-4 years.
I'm still bothered by the hard top hose. Should be able to easily squeeze it.

[extremrovers]

When Is Hot You Cant Squeeze The House Is So Hard And Inflated Is Like Something Is Blocking The Coolant Flow From The Radiator To The Termostat All Other Hoses Are Ok (the Bottom One ) .timing Is Ok..the Fan Is Costing When Hot I Will Get A New Fan Clutch Anyway But I Don't Know If Is The Clutch...i Will Take The Termostat Out To Day And See What Happens !!

[OkieRover]

I too am bother by the hard hose. Have you had a hydrocarbon test done on your coolant?
You might not be loosing any, especially since you replaced all the hoses. Once my head gaskets started to go, I popped a hose every couple of days and only the old ones.
How sure are you your radiator is good?
I had to have mine rodded once a year before my head gasket gave out completely. I finally replaced it with a new one after we did the head gasket job and have had no trouble since. (knock on burled poplar).

[extremrovers]

last night i took out the thermostat and still the same thing it takes a little longer to overheat but the same thing...( ONLY UPPER HOUSE IS HARD..?) this is what i don't get if it overheats why ..the check engine light dose not come on ? how and where do you test hydrocarbon in coolant...? i will have my radiator tested to day and see..iam thinking about replacing radiator and fan...what else ..?

[TerryS]

Direction of flow is FROM thermostat housing TO radiator, so if thermostat is opening as it should, and top hose is that hard, and bottom hose isn't, then your radiator must be severely blocked. If fan clutch is just coasting, then it isn't in lockup and thats just compounding the problem. Better no run it till you get good flow, or a severe overheat will lead to liner issues.

Hydrocarbon test for combustion gasses in coolant is very simple. See the other current overheating thread for the procedure(s)

[extremrovers]

thank you...!!!!!!!

[extremrovers]

i got a new radiator i will installed to day see if it works thank you guys for all your help..!!!

[dsfloyd]

Hopefully it works, definately sounds like something is blocked.

[lwbblue]

Terry S is one of the most knowledgeable voices on the board; I always look for his responses. That said, I'm looking at the radiator as your problem. My 95lwb and I live in Az; we see hot a lot. When driving and not cooling with all that air, check the rad. Rover rads clog easy; It needs to be rodded or replaced with a quality unit. If you over heat, all kinds of stuff gets loose and is moving around in your system. Reparing or replacing the rad will work for awhile, until it collects the rest of the stuff that's still in the system. Two rods or cleaning the new rad will usually do the trick.

I installed a mechanical gauge, putting the sensor in the top of the rad at the threaded hole. Many people criticize me saying it doesn't tell true blah blah blah. What it does do is give you a heads up on the changing of the water temp and an early warning of trouble. The water in my truck rarely gets to 212, and that’s cool! I can see a drop of 15-20 degrees by turning off the air cond on hills.

Sorry for so much, hope it all helps

geneo

[extremrovers]

thank you guys... i have installed the new radiator to day and now it seems to work great i haven't had the chance to test drive for more then 10-15 miles but it it looks to be ok (NOT OVERHETING) i will take a longer trip later to day and let you guys know....do i have to put back the tremostat now that i have the new radiator or it can be with out ..?