1.9 petrol Z3 running cold?

TriumphZ3

TriumphZ3

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Hi all... went for a Classic Car run yesterday, me leading a dozen older cars through country roads at about 30 mph... but I noticed the Z3 seemed to be running very cold going by the gauge. I need to flush the coolant (which I suspect is just plain water, although very clean and clear) but can't get the cover off the underside of the car to get at the radiator, plus I've already purchased a new thermostat to replace at the same time, but this seems very cool. The heater was on, and working very well going by the heat, but should the heater drop the engine temperature so far? Even with the heater off, and total distance of maybe 60 miles covered, it never went above the first white mark on the gauge even when idling in our arrival car park. Any thoughts?
Any advice on removing the large undercover plastic panel below the radiator will be appreciated too, I've had the car on the ramp twice and no matter how many visible bolts and screws I remove, it won't move at all. All pointers appreciated!
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Could be; I've got a new one as a matter of course but can't get the radiator out to replace it, as I can't get the bottom cover off down below... :)
 
An easy way to check if the thermostat is stuck open, is to let it tickover and drape a blanket, or big towel over the grilles and under scoop, holding it in place with the bonnet. It is amazing how quickly the heat builds up.

I did this recently on my daughter's Mini to check the cooling fan and new thermostat when I recently changed it. Worked a treat on a cool September evening! 👍
 
Duncodin said:
Does the radiator need to come out to get at the thermostat near the top of fhe block?
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No. I replaced my thermostat without removing the rad; plenty of room with the M44
 
Just an update...(been a busy day!!)
Drove the Z3 for 30 miles, dual carriageway speeds, temperature went above the first white mark but not to halfway. As I had the heater on blower mark 2 on Saturday would that really have lowered the engine temperature so much?
As I'm completely new to Z3s I've just had to go by how-to's online and the first one stated to remove the radiator, remove the viscous fan, and replace the thermostat that way. I can see it on front of the block, so is there room?
I really need to drain the system and refill properly, it's back on the lift tonight but I still can't work out how to remove the huge plastic undershield. I've removed about eight screws al round, can't see any more, but it's still solidly in place.
 
I have always read that the needles sit dead on the center white mark. Mine (M54 6 cylinder) always reliably does, and typically gets there within 5-10 minutes if the temperature outside is at least 15 C or so. Not sure about lower temps. The gauge sits on center for a wide range of engine temperatures (I see reports anywhere in the range of 180-200+).

I suspect that something is amiss, but I don't know what to suggest. The internet says stuck thermostat, as suggested above.
 
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Pond said:
An easy way to check if the thermostat is stuck open, is to let it tickover and drape a blanket, or big towel over the grilles and under scoop, holding it in place with the bonnet. It is amazing how quickly the heat builds up.

I did this recently on my daughter's Mini to check the cooling fan and new thermostat when I recently changed it. Worked a treat on a cool September evening! 👍
Click to expand...
An easier way to check is to start it up from cold, lift the tick-over a bit to help it warm up quicker, and try keeping your hands on the heater hose at the back where it goes through the bulkhead and the radiator top hose. If the thermostat is working properly the heater hose will be pretty much untouchable before the top hose starts to get warm, if the thermostat is bu**ered they'll warm up at the same rate. Beware the fan-blades, obvs.
 
Thanks for the replies, welcome as always. I've managed to get the undertray off (two high-up screws I hadn't seen) so am trying to drain the system which is now light brown water. I'll flush it a few times then see how things go before touching the thermostat, although a new one is sitting in the box waiting. It makes sense to change it now, though.
 
TriumphZ3 said:
Thanks for the replies, welcome as always. I've managed to get the undertray off (two high-up screws I hadn't seen) so am trying to drain the system which is now light brown water. I'll flush it a few times then see how things go before touching the thermostat, although a new one is sitting in the box waiting. It makes sense to change it now, though.
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Draining and flushing the cooling system is far more difficult than changing a thermostat, so you might as well do that while the system is empty IMHO.
 
Pond said:
Draining and flushing the cooling system is far more difficult than changing a thermostat, so you might as well do that while the system is empty IMHO.
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That's easy for YOU to say....!! :D
Just in for a break, system drained but have got both top bolts out of the thermostat, the other two are practically unreachable with the fan still in place. Cup of tea then back to the chase.
 
TriumphZ3 said:
That's easy for YOU to say....!! :D
Just in for a break, system drained but have got both top bolts out of the thermostat, the other two are practically unreachable with the fan still in place. Cup of tea then back to the chase.
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Working on modern cars (or even semi-modern) is never easy, is it?
 
Pond said:
Working on modern cars (or even semi-modern) is never easy, is it?
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Lol but made easier by people on here that I can bounce ideas off or go to for moral support.
Got it done, the fan had to come off so the shroud had to come off first to get access; thermostat now changed although the old one was quite clean and didn't look at all stuck. Am currently refilling with the front of the car raised to about 45 degrees and we'll see how things go after that.
 
The thermostat doesn't have to be stuck, can fail by opening too early. If you've got a thermometer and a small saucepan with some water you can try testing it. Won't make any difference if you're already changing the 'stat but it's nice to confirm that there was a problem there to start with.
 
Also an infra-red thermometer is very useful for chasing cooling system issues. Inexpensive these days on eBay.

Tony.

ps. Also useful for finding binding brake problems too.
 
Just to update anyone reading the thread, took the Z3 out for the first long run today and the needle now points straight up to the centre mark; very very slightly over it towards hot but not to a worrying extent. The old thermostat appears to have been running cold. It was also a different design, a bucket-type end with the new one just being a flat disc. I'll see how the car behaves over the next while but the coolant seems to be at the correct level and is now blue rather than clear.
 
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