One way to check indirectly if the cooling system is working properly is to measure the time from starting the engine till reaching half-scale (90C) on the T gauge. Please post your results in this topic for comparison purpose.

 

Here are my results when I leave home early in the morning.

 

Outside temperature: 12C (freezing cold, man...)

Warmup time at idle: 12' 30"

Warmup time driving in town: 10'

Warmup time driving on highway: 6' 30"

Edited 16 March, 201511 yr by RicardoM

Good idea this, i'll check what mine does tommorow morning, its much colder and much more humid here.

I believe any overheating, heater matrix or thermostat issues could be spotted with this easy, money-saving  test.

I would like to join in your research but BMW do not fit temp gauges, so I can't.

1.9 diesel model, outside temp 4 deg c

warm up time at idle over 25 mins, had to adandon that test.

warm up time in town, 33 mins

warm up time at highway speed (light to medium load) 13 minutes

with new pattern part thermostat and roughly 60/40 mix of vw g11 blue coolant and deionized water, suspected hairline crack in heater matrix core because occasional smell of coolant through fresh air duct during warmup.

33 minutes!? Not familiar with Diesels, never owned one, do they heat up less during winter compared to petrol engines?

I guess the thermostat is not closing properly OR the thermostat metal body is not sealing when put inside the plastic housing. The latter happened to me when I noticed the upper radiator hose was hot on its entire length from as low as 70C... so I made first a thin O-ring out of high temp. liquid gasket (1), let it cure 3 minutes, then seated the thermostat (2), then inserted the circlip (3). This trick almost halved the warmup time of my engine!

 

Edited 19 March, 201511 yr by RicardoM

Diesels just naturally run a lot cooler than petrol engines, i am fairly certain theres nothing wrong with the thermostat too because once upto temperature its rock solid.

i am fairly certain theres nothing wrong with the thermostat too because once upto temperature its rock solid.

Same thing happened to me, rock solid after reaching 90C, yet it took 20 minutes to warm up at idle because hot water was seeping around thermostat metallic shell from little circuit to big circuit. Initially to me didn't seem a big deal some under 1 mm space to seep, but once sealed... upper radiator hose got warm only at 88C as it should.

 

Edited 19 March, 201511 yr by RicardoM

Can anyone else share data, please?

See first post.

Edited 2 April, 201511 yr by RicardoM

You can't compare petrol and diesel engines for warm up time. I've even seen a diesel get cold on idle. We used to spend a few nights on on site standbye and ir was common to get a Transit ,take it for a drive ,then settle down with heater on low. Any more and it got cold. And on frosty nights i've had to go for a drive mid way through.

VWD

TeflonTom already clarified the matter relating to diesel engines warmup time.

Do you own a Skoda Felicia and have specific engine warmup time to share?