Thermostat/temperature issues

RoaryRati

Member
Messages
1,582
Not sure whether something is wrong or not - so I plea for help. Recently had a new heater matrix (old one had been leaking, probably for at least a couple of years....another story). OK I've been driving in chilli-ish conditions (outside temperature from 4degC - 8deg C) but this is what happens to the temperature gauge and is it normal, or do I have a problem. Idling for 5 mins and the temperature gauge rises to 90deg. Get driving again and within 5 mins or so the temp gauge is back down to the line between the 50 and 90 line (I'm guessing 70 - but honestly haven't a clue). Also the bonnet and wings no longer seem to get hot to the external touch, so I can wash the car as soon as back from a runout - this has not been possible in the past.
(Meanwhile the engine warning light is now on following a dodgy start up when stopped for 10 mins half way through a 60mile run out but once going the car is running fine).
Many thanks to anyone who can help.
 

CatmanV2

Member
Messages
48,547
At a guess your thermostat is stuck open (or at least partly open)

Get a cheap OBD reader to find out why the engine light is on

C
 

FIFTY

Member
Messages
3,100
My car does the same thing in traffic it goes up to 90C and in "clean air" it is down to 65C it does suggest an open thermostat but the car seems to run pretty happy in these conditions. I found a DIY where a forumer changes the thermostat and it continues to run like this so not sure if the new thermostat also be stuck open?

http://www.sportsmaserati.com/showthread.php/9347-4200-Thermostat-Replacement

I'm planning on changing the radiator, thermostat and all hoses in the next year or two so I'll find out myself. I have already had a new fan relay installed, as long as the temperature does not go over 90C which can cause more damage.

Engine light could be anything as C mentioned invest in a ODBII reader from Amazon or Ebay
 

conaero

Forum Owner
Messages
34,593
Sounds normal but you could have air in your coolant system from the matrix change?
 

davy83

Member
Messages
2,809
temperature does change between running on an open road and sitting still, typically open road 65-70 and once static in traffic it will climb to 90. Engine warning light however is a different problem.
 

hladun

Member
Messages
149
What do you have...3200 or 4200? The 4200's must have the air bled from the heads or you're asking for trouble. A CEL is not "normal" and you need to read it to see what it is. A working thermostat can hold the temp steady and should not wander around as you drive.
 

Boomerang_GT

Member
Messages
202
The lower temp is while driving an the thermostat openes. Usually with old thermostat it’s lower than it should be.
The higher temp is when the cooler fan switches on.
 

Zep

Moderator
Messages
9,110
I had this and changed my thermostat. It was exactly the same afterward. I think it really is a case of “they all do that sirâ€.

My view is that the temp sender is on the return from the radiator to the water pump rather than the pipe from the engine to the rad and so reads low.
 

Kookaburra

Junior Member
Messages
32
Yep, mine too. Runs around 70C on the gauge open road then rises to 90C in traffic/very slow before the big fans kick in which then keeps temp =< 90C even when stopped in city traffic.
 

rusty iron

Junior Member
Messages
73
Mine used to do that and it was the resistor at the bottom of the rad that was fritzed and was not turning the lowest
Speed fan on.
 

RSM Masser

Member
Messages
2,437
Mine does exactly the same. I would swap out the resistor mind you. It’s easy and very cheap (which is unusual)
 

RoaryRati

Member
Messages
1,582
Many thanks guys for your responses - and I took the move of taking the car back to my local Italian car mechanic (NJS in Pershore). He put it on the diagnostics and that highlighted 4 issues!!! - The Lambda sensors (or something like that) which apparently should be changed every 4 years (but people rarely do because they are expensive), something with the battery (we do now have to keep it on a CTEK, I think, charger when its not in use because the battery is draining - it never used to) and something with the clutch and something else, which I can't remember (yes, it was a LOT for this 100% unmechanically minded person to take in). So the poor little car is awaiting attention (and I have to save like crazy)...........
 

davy83

Member
Messages
2,809
Tragically sounds like nothing on the list that has any bearing on the engine temperature? Its not unusual to have a list of niggly problems with these cars, they are pretty fragile, so if you cant fix any of them you had better get a good relationship with you local garage!
 

Boomerang_GT

Member
Messages
202
Lambda Sensors cost less than 100€ the pair.
But 4 years cycle is exaggerated. Thought I immediately felt an increase in performance and less fuel consumption when I changed mine. Think the old ones were the first on that car.
 

Gp79

Member
Messages
1,393
Lambda Sensors cost less than 100€ the pair.
But 4 years cycle is exaggerated. Thought I immediately felt an increase in performance and less fuel consumption when I changed mine. Think the old ones were the first on that car.

Yes, buy the lambda sensors from Bosch not maserati as they will be half the price for the same part.