[james]

My '89 RR Classic is a bundle of problems, but the cold weather has brought this to a head.

I can't seem to get much heat out of the heating system. Maybe I'm just expecting too much, but I'll describe the problem.

The temp gauge on the dash never really moves from the left. This could be a symptom of a dodgy temp sender, or something else. On cold days, I can have problems heating the cabin to a pleasant temp. The heat is working, but just not very well. From what I've read, it seems like the heater core might be a culprit, but are there any other ideas?
Thanks,
James

 

[TimoV]

Change the thermostat. If the temp gauge does not move into the middle of the range, it is the most probable cause of coldness.

 

[james]

Aha, that might fit in with another piece of the puzzle.

Do RRs control their radiator fan by the same thermostat? The reason I ask, is even when cold, on cold days the radiator fan will always run...

Thanks!

 

[james]

I'll replace the thermostat and gasket, as they're cheap and if it isn't that, no big deal.

Does anyone know whether it's best to use a 160, 180, or 195 Degree Fahrenheit thermostat? The Haynes manual gives me the temp in Celsius, and I also hear there is a difference in how the UK and US define the temps, one is when the t-stat starts to open, and the other is when it's fully opened (or something)

Anyone know what the best degree rating is to use?
Thanks,
James

 

[Eric D]

James you should have a viscous fan clutch on your water pump. This fan clutch should engage when hot.

I've had several new aftermarket brands that never seem to work right, they are always engaged and my fuel economy suffers. Avoid Allmakes brand.

I'm looking for a single multi-speed OEM fan from a domestic or foreign vehicle. I need to see what is available with 3 speeds, I have a VW fan control module that will control all three speeds from the different sensors on my motor. It could also be used to drive an aux. water pump in-line with the heater core. This is programmed to run for 5 minutes on an 8 pin module or 8 minutes on the 10 pin modules.

You'll want a stock temp thermostat (88ºc-90ºc, 190ºf-195ºf) so your EFI doesn't go into closed loop.
Too cold and your dumping fuel out your tail pipe.

Find a stock temp t-stat with fail safe if you desire. If you get a regular t-stat, get one with a jiggle pin, these allow air to purge the system. Install the pin or hole facing upward at the 12 o'clock position.

If you don't have a jiggle pin, you can always drill a hole, 1/8" or 3mm is fine.

 

[TehPriest]

Aha, that might fit in with another piece of the puzzle.

Do RRs control their radiator fan by the same thermostat? The reason I ask, is even when cold, on cold days the radiator fan will always run...

Thanks!

Is your fan electric? If not then the answer is no. If it is and you haven't got it confused with the air con then it is a owner fitted unit. Follow the wiring back to find the thermostat. If you have air con and it is these that are running then check they switch is set to off (second position drom the right) and if it is then the fun begins trying to find the fault.

ray:

 

[james]

You'll want a stock temp thermostat (88ºc-90ºc, 190ºf-195ºf) so your EFI doesn't go into closed loop.
Too cold and your dumping fuel out your tail pipe.

Thanks for the responses.

The Haynes manual defined the 'opening' temp of the thermostat as 173-182ºf, so I was going to aim for the 180ºf version. Do you think the 195ºf version would be more economical on fuel usage?
Thanks,
James

 

[james]

Is your fan electric? If not then the answer is no. If it is and you haven't got it confused with the air con then it is a owner fitted unit. Follow the wiring back to find the thermostat. If you have air con and it is these that are running then check they switch is set to off (second position drom the right) and if it is then the fun begins trying to find the fault.

ray:

Hmm, it's the main big fan in the engine, I thought this was the radiator fan. I'll double check this weekend when I'm replacing the thermostat. I'm pretty certain it runs constantly, so I'll trace back the wires as you suggest and see what's going on.
Thanks,
James

 

[Eric D]

You'll want a stock temp thermostat (88ºc-90ºc, 190ºf-195ºf) so your EFI doesn't go into closed loop.
Too cold and your dumping fuel out your tail pipe.

Thanks for the responses.

The Haynes manual defined the 'opening' temp of the thermostat as 173-182ºf, so I was going to aim for the 180ºf version. Do you think the 195ºf version would be more economical on fuel usage?
Thanks,
James

James, my Bentley manual states 88ºc/190ºf is the proper temp thermostat for a V8.
It says the lower temp thermostat is for diesel engines.

I use 88ºc/190ºf here in sunny California.

I've never been a fan of Haynes manuals.
I prefer Robert Bentley, Mitchell/ Mitchell on Demand and Chilton, all are available in paper back and books, CD/DVD and on-line subscription.

 

[james]

Thanks Eric, I just picked up a 195F thermostat.
The guy at the parts shop said he had that listed as the original equipment, so it's good to have a consensus.

One more question. The part I purchased does not have the small air hole in it (that sits at 12 o'clock). The Part Shop Guy said as this was the recommended part, it should not be an issue.

Anyone have any opinions as to whether I should drill a small hole in the new thermostat?
Thanks,
James

 

[Eric D]

James, it is cheap insurance against trapped air.

I drill the hole in every thermostat that doesn't have a jiggle pin.
I also own a coolant system pressure tester that I used to purge air in the system. This makes quick work of this job, otherwise you'll be standing around waiting for the coolant to heat up, pinching hoses, purging air, refill, and repeat the process.

The tool is used on a cold engine (used hot to determine coolant problems), and I picked mine up many years for off ebay.
I paid about $130 shipped, I've seen this same tool being sold by Matco for over $400.

Harbor Freight has a cheaper version, just make sure it comes with an adapter that fits your Rover (should be the same as BMW).
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=65053

 

[james]

Eric, Thanks for the continued assistance.

What diameter hole would you use?
Thanks,
James

 

[Eric D]

James, I posted in my 1st reply that you should drill a 1/8" or 3mm hole.

Make sure you use a commercially available coolant flush product. I suggest a heavy duty version that will get the job done.
Some products suggest you drain and flush after a few heat cycles. I doesn't hurt to run it a few days and drain.
You basically want to rid your system of any silicates if your running green coolant.

Also check your hoses on the inside. Run your finger and wipe the inside of the hose. If you see black residue, this is your hose breaking down.
This type of wear is called striation, a split will form and eventually you'll have a leak.

So make sure you have good hoses.

 

[james]

James, I posted in my 1st reply that you should drill a 1/8" or 3mm hole.

Sorry, I did read that, but I got so focused on the temp rating that I forgot.
James

 

[james]

So, drilled the hole. All good.

I don't know if my RR has an aftermarket radiator, but I could NOT find the radiator drain plug. After 30 minutes looking and getting increasingly frustrated, I decided to siphon the coolant out.

Got the coolant out, eventually got the thermostat holder (or whatever it's called) off after struggling to get to the bolts (the distributor was in the way, I probably should have removed it first). New thermostat in, cleaned off all the old junk, new gasket, all back together, coolant back in and took out for a test drive.

It looks like the temperature needle does climb higher than it used to, but still seems to top out at around a third. It may have felt like the heating was warmer too, but I really wanted it to feel warmer, so I'm not sure.

Got home, and found I was dripping a bit of coolant, so re-tightened the two bolts and the hose clamps that I had removed. Tomorrow when it's cool, I'll top the coolant up again, and see how it goes from here.....

Thanks for the advice,
James

 

[classicjack]

Remove lower rad hose to drain rad. Remove filler plug in rad and in metal tower on heater hose in engine compartment , start engine and pour water into heater tower until it comes out of radiator filler hole, this will bleed system of air and ensure heater core is getting coolant. Usually poor heater performance is from no coolant in core, since it sits so high in the system its the first place coolant leaves when system is low. When you change thermostat you should bleed system.