SIIA 109 overheating

[rwollschlager]

My SIIA 109 (petrol) gets really hot after driving even a short distance. The needle is pegged in the red after about 2-3 miles of driving.
Here is what is bothering me:
-The thermostat is good and has been checked (pops open at 180).
-The radiator is not clogged and it does have flow.
-The water pump is new, and water is definatley flowing because the upper and lower hose are both hot.

Is there another key element of the cooling system I am forgetting that is causing the truck to overheat?
I doubt the gauge is wrong because 2 head gaskets in 3 years confirm the truck is overheating. (Since then the head has been checked by a machinist so its ok)

[daveb]

what about at idle. does it overheat then? perhaps there is a brake binding? how do you know the rad is not clogged? you cna check the surface with an IR thermometer to make sure it is more or less the same temp all over.

last but not least, if you are using an electrical temp gauge then check the connection @ the sender unit. could be a bad sender or gauge.

is the timing etc all set properly?


My SIIA 109 (petrol) gets really hot after driving even a short distance. The needle is pegged in the red after about 2-3 miles of driving.
Here is what is bothering me:
-The thermostat is good and has been checked (pops open at 180).
-The radiator is not clogged and it does have flow.
-The water pump is new, and water is definatley flowing because the upper and lower hose are both hot.

Is there another key element of the cooling system I am forgetting that is causing the truck to overheat?
I doubt the gauge is wrong because 2 head gaskets in 3 years confirm the truck is overheating. (Since then the head has been checked by a machinist so its ok)

[scott]

running to lean of a fuel air mix will cause it to run hot

[Les Parker]

Has the dist. timing been checked?
If too advanced, it can cause issues.

[CliftonRover]

Rob if you can get it to my house on the 8th earlier say 10:30 in the morning I could check it out for you. If it is actually getting hot, which think I remember from the metal dash rally that it is, when was the radiator recored last? other than that is would have to be either timing or the fuel air mix. I am sure you guys have checked this stuff already though.

[rwollschlager]

The truck does not overheat at idle, right after we put the water pump in we let it run for about an hour at a high idle with no signs of overheating.

The distrubutor and timing was checked along with the points re-gapped after the head gasket job in july and it runs good. (no coughs or sputters after i turn the key off etc.)

I will get a hold of an IR thermometer, and check the fuel/air mix. The temp sending unit was also replaced with the head gasket in july, but that does not mean the connection is good, so i will check that too.

Thank you for all your help!

Forrest, we should be able to get the truck to your place on the 8th if i dont get this sorted before then. I havent even touched the low range issue yet...:eek:

[gudjeon]

Is there a significant temp difference between upper and lower rad hose? If not, I would suspect the rad.

[Terrys]

Has the dist. timing been checked?
If too advanced, it can cause issues.Too true, however, equally it will run very hot if too retarded (your pipe will be glowing)

[CliftonRover]

Alright Rob sounds good there will likely be other rover geeks there to help.

[Linus Tremaine]

I belive that the voltage stabilizer can cause the gauge to read wrong. Mine reads at the red all the time, but the IR thermometer shows that its running pretty normal.

[adkrover]

Is this a problem that has gotten worse or has it always been this way since you've owned it?

Aside from what everyone else has suggested, do you have a radiator shroud on the back of the radiator to maximize the vacuum created by the fan? Mine was overheating a bit until I added a shroud. Now temp is steady.

[Jeff Aronson]

All good recommendations, and here are some other thoughts:

When you changed the water pump, did you install the fan correctly? If you reversed it, the air flow will be reversed and you might overheat while underway, when at idle, the car circulates enough water because of the new pump. I remember being rather baffled when I removed mine to replace a water pump as to just which way was correct.

Also, high idle is still much less than the friction generated at speed, so I'm suspecting that you're not circulatinig enough water. If the radiator doesn't leak, it might still be quite clogged. Have you have it examined by a radiator shop? How old is the radiator?

Lastly, do you get heat from your heater when the car is running? Are you getting a proper flow through the heater unit? If you have too much air in the system, you may have a sort of "vapor lock" at work. Unlikely for sure, but possible - I had it happen once.

Good luck and let us all know what you find out.

Jeff

[scott]

i like that backozward fan theory. i wouldn't have thought of that. before rip'n my moor out i used to cruise with a leaky radiator such that i wouldn't bother with antifreeze/collant. used staight water and it was always a gallon low because of where the leak was and mine never ran hot.

[109 Pretender]

All good possibilities above to ck for sure. However, you mentioned that it ran fine at idle then went to overheat very rapidly when driving a short distance. That pretty much centers the prob on the advance weights in the dist. being stuck. You are probably running very retarded on the dynamic advance. My 6cyl 109 did this exact thing once many years ago. I drove it less than 1/4 mile before pulling over - the exh. mani. was glowing - literally. WD-40 and some elbow grease freed it up. (Another symptom of this is very sluggish performance.) If the mixture was really that weak it'd be popping and very noticable. Stuck adv. weights will not be evident at idle at all - but it'll show up instantly when trying to drive. You can ck the total adv by using an adjustable timing light - this will take into account the static setting + the vac. adv.+ the mechanical weights. I'm not sure what the total should be - probably around 32 or so degrees (assuming around 6 degrees BTDC static and stock dist.). When cking this way - rev engine to around 3K - all avail. advance should be in at that speed - then dial the timing light back to TDC and read the total advance it took to do so.
Worth a ck. because it sounds like you are on top of pretty much everything else that could cause problems.

Good luck!

[Donnie]

My SIIA 109 (petrol) gets really hot after driving even a short distance. The needle is pegged in the red after about 2-3 miles of driving.
Here is what is bothering me:
-The thermostat is good and has been checked (pops open at 180).
-The radiator is not clogged and it does have flow.
-The water pump is new, and water is definatley flowing because the upper and lower hose are both hot.

Is there another key element of the cooling system I am forgetting that is causing the truck to overheat?
I doubt the gauge is wrong because 2 head gaskets in 3 years confirm the truck is overheating. (Since then the head has been checked by a machinist so its ok)
DOES IT OVER HEAT WHEN SITTIN STILL? anybody ever put a fan on backwards, it will cool when not moving, pushing air out the front, but it becomes a battle for air flow when the unit starts rollin' down the road,,,ask me how I know.............Dipstick

[rwollschlager]

thanks for all of the advice!
After running the truck while in the red, examining every last part of the cooling system, we noticed the truck was not getting hot at all. the IR thermometer read 130 (F) at the temp sender and around 90(F) at the radiator itself. Turns out the new temp sender unit we installed in the summer was bad out of the box!