Series 3 running hot

[Paul Rossmann]

The old girl is running hot. In stop and go traffic the needle quickly moves into the lower part of the red. Once moving, everything seems fine. I have flushed the radiator and engine cooling system and replaced the water pump and thermostat.

I ran the car for 2 years with just an auxillary electric fan and she did okay. The thermastat (for the electric fan) gave out, and I put the original mechanical fan back in, but to no avail.

Any ideas.

[Jim-ME]

For the cost, I would replace your temp sender before going any further.
Jim

[greenmeanie]

A couple of things to check.

1. This may be offensive but check the mechanical fan is the correct way round so that it pulls air and doesn't push it.
2. Do you have the cowl in place - it makes a huge difference to the fan efficiency.
3. When she starts getting hot feel the top and bottom radiator hoses. If one is significantly cool you have a blockage.
4. Hold your hand close to the radiator (Don't touch it because that will hurt) and feel for cool spots. If you are fancy and part of the modern world you can get one of those optical thermometer gun things to take readings.
5. How new are the hoses? They can collapse internally partially blocking the coolant flow.

Flushing a radiator can help as part of maintenance but once blocked it very rarely ever shifts the problem. A clogged radiator really needs to be rodded or replaced.

The series cooling system is overbuilt for the original engine and if in good order tends to overcool if anything. A couple of years ago I replaced the water pump, hoses, fan and radiator due to an errant socket left on the crankshaft end nut (Not one of my prouder garage days and a bit of a brown trouser moment with the bang when it came off.). Now I have to put the radiator muff on when it falls below 50° and she only gets up to maybe 3/4 on the gauge during the height of the Phoenix summer.

Cheers
Gregor

[Paul Rossmann]

Thanks, I will give that a try, but the temp starts at "zero" and progresses up normally. When the car is moving along at 35-40 the temp is normal (after a few minutes). It is when the car is stopped or in stop-and-go traffic. I did pull teh sensor to make sure it wasnt just gunked over, and it looked clean.

[Tim Smith]

Could you have the idle set too lean? Or is the idle set too low so that the fan doesn't pull enough at the street lights?

Kind of guessing here. :confused:

[singingcamel]

A couple of things to check.

1. This may be offensive but check the mechanical fan is the correct way round so that it pulls air and doesn't push it.
2. Do you have the cowl in place - it makes a huge difference to the fan efficiency.
3. When she starts getting hot feel the top and bottom radiator hoses. If one is significantly cool you have a blockage.
4. Hold your hand close to the radiator (Don't touch it because that will hurt) and feel for cool spots. If you are fancy and part of the modern world you can get one of those optical thermometer gun things to take readings.
5. How new are the hoses? They can collapse internally partially blocking the coolant flow.

Flushing a radiator can help as part of maintenance but once blocked it very rarely ever shifts the problem. A clogged radiator really needs to be rodded or replaced.

The series cooling system is overbuilt for the original engine and if in good order tends to overcool if anything. A couple of years ago I replaced the water pump, hoses, fan and radiator due to an errant socket left on the crankshaft end nut (Not one of my prouder garage days and a bit of a brown trouser moment with the bang when it came off.). Now I have to put the radiator muff on when it falls below 50° and she only gets up to maybe 3/4 on the gauge during the height of the Phoenix summer.

Cheers
Gregor
Good Advice here:thumb-up:

[Paul Rossmann]

Thanks all for the advice. This is a real stumper as the cooling systems are so simple. My engine idle is around 1100 so it isnt that. Brakes arent binding (the car gets hot standing still) I have replaced the waterpump and thermostat. The gauge climbs up normally, so I dont believe it is the sensor. The other day when the car was hot, after very carefully opening the radiator cap, I removed the lower hose to drain the radiator quickly and ran a garden hose (cold) into the radiator while checking for "dead" spots. The radiator got cool evenly so I cant figure that out. I hate to go to the expense of a new radiator, but I cant figure this out. Is there anything with the heater hose, or heater itself that could be doing this? Again, I appreciate the input.

Rovering against better judgement,
Paul

And yes, the fan is the right way round. I actually thought of that in the middle of the night last week and had to go out and check (sick, huh?).

[greenmeanie]

Your idle seems pretty high @ 1100 rpm. The book quotes something like 600rpm for the early pre emissions trucks and 825rpm for the later models with PCV valves & charcoal canisters.

If that is as low as you can get her to go smoothly I would suggest that you are badly out of tune. I would go back and play the timing/fuel/idle game and see what that does for you. It's a cheap place to start.

Cheers
Gregor

[SalemRover]

It seems that when there is good airflow your cooling system works fine. If it was blocked you would not cure it quickly by getting up to speed. It could be that going back to the stock fan you simply uncovered a problem that was simply masked by the electric fan. Idle being lean is a good idea to check. Lean exhaust should be fairly easy to diagnose, if unsure just run a little richer on the carb noting how much you moved the screw so you can go back. Lowering the idle RPM back to stock (even if it is rough... you can deal with that seperately) should also help as well.

Good Luck,

Jason

[Paul Rossmann]

Just drove the Rover home from work. She was not overheated, but in the upper range on the gauge. As soon as I stopped the car, I got out and felt both the upper and lower radiator hoses. The lower hose was noticably cooler than the upper hose (warm vs. hot). I am now thinking that in addition to the possible idle/timing/lean mixture issue, that it may well be the radiator. Perhaps a partial blockage? Can this be reasonably repaired? Hmmmm?

[greenmeanie]

You could try running a citric acid radiator flush. Follow the instructions and if your lucky that will move stuff. More likely take it off and go and get it rodded. It shouldn't be expensive.

Cheers
gregor

[sayers]

I had my radiator done for around $50.00, just a thought. good luck

[LaneRover]

The lower hose was noticably cooler than the upper hose (warm vs. hot). I am now thinking that in addition to the possible idle/timing/lean mixture issue, that it may well be the radiator. Perhaps a partial blockage? Can this be reasonably repaired? Hmmmm?

If I am correct the lower hose should be cooler than the upper hose as that is the coolant that has flowed through the radiator.

Just a thought but do you have the radiator fan shroud on? Without it that fan may just be pulling air from around the radiator and not through the radiator. Is there any chance that though your fan is turning in the right direction it may be the wrong fan? Or that the blades have been bent (or in this case unbent) so that they don't pull as much air?

Brent

[Paul Rossmann]

You are correct, the lower should be cooler... The shroud is in place. I will adjust the carb as well as the timing this week. I have the "electonic points" so the timing is a bit advanced. My understanding is that is normal, but will listen to any discussion that says otherwise (?)... but could the timing being slightly off (the car runs fine—not fast, but fine) and/or the mix running lean make the engine run that hot?

[Tim Smith]

You are correct, the lower should be cooler... The shroud is in place. I will adjust the carb as well as the timing this week. I have the "electonic points" so the timing is a bit advanced. My understanding is that is normal, but will listen to any discussion that says otherwise (?)... but could the timing being slightly off (the car runs fine—not fast, but fine) and/or the mix running lean make the engine run that hot?
Running lean could definitely make you run a little hotter. If I'm not mistaken, having the ignition too advanced could boost your temps as well.

I'm not entirely sure that either of those is the culprit though. At least not alone because you didn't make any recent adjustments to either. Right?

Maybe the electric fan was over compensating for a few minor issues that are just now coming to light?

[sven]

If I'm not mistaken, having the ignition too advanced could boost your temps as well.

Yup, this is true. Unfortunately I learned this the hard way. :(

[Paul Rossmann]

I am stumped. One would think that as simple as the cooling system is on an old Series that it wouldn't be that hard to trouble shoot. I have now "riched-up" the carb, and reset the timing. It is now as advanced as it will [smoothly] run with the Petronix. She is still running hot. The only things that I haven't done is have the radiator rodded. It seems fine, and as mentioned before the lower hose is noticably cooler than the upper once the car gets warm. That, and I have not replaced the temp sensor because the gauge seems to progress normally. Meaning that It starts out cold and gets warmer after about a half mile or so... it just doesnt stop rising till it is right under the red. And then, if I get in stop and go traffic it creeps up barely into the red.

Any ideas?

Thanks in advance.

[Tim Smith]

... and reset the timing. It is now as advanced as it will [smoothly] run with the Petronix. She is still running hot...
Actually you want to set the timing as retarded as possible. Running it advanced will boost the temps.

[gobie desert]

timing will get it to run hot too far advanced, but i would really get the rad boiled out by a pro. even it if seems somewhat clean you could have some major issues going on in there. better yet get an aluminum unless you are looking to keep the stock look and feel. but boiling it out should be enough. 50-90 bucks depending. that way you know it is not the problem then move on to the next simple thing.
what temp was the thermostat?

well good luck.

[SalemRover]

From your original post it seemed that once moving you were fine, but now it seems that isn't so or was just not stated clearly enough. Under those assumptions of cool when moving and hot when not it would seem that airflow across the radiator would be the biggest culprit, or your suspect idle conditions. So now it appears that under most (if not all conditions) you run hot. I think we can safely say that we can rule the fan and temp gauge out of the question. You also said the pump was recently done as well. Assuming you dont have some sort of ridiculous blockage in the block it appears that you should turn your eyes back to your radiator, and thermostat(the one in the head, not the gauge). Afraid I can't help much with your radiator diagnosis.

Best of luck with it!

-Jason

[Paul Rossmann]

Sorry my reports seem so inconsistant. The weather here has been between 32 and 80 degrees, so the "cooling down" when the car gets up to speed is equally inconsistant. I am pretty much resolved to pulling the radiator and have the pros do whatever it is that they do to clear them out. My opinion at this point is that the radiator is partially blocked. Or blocked just enough that the car will get hot if there is only a minimum air flow over and coolant flow through, but cools down once water and air flow increase (i.e. with higher engine fan/water pump revs and higher road speeds).