Engine not fully heating up

Random Caddy chat.
Not the place for sale or wanted topics.
Pinnacle100
Caddy Fan
Posts: 53
Joined: Sun Oct 15, 2017 8:51 pm

Engine not fully heating up

Post by Pinnacle100 »

My 1.6 tdi seems to struggle heating up fully . It CAN heat up to 90 degrees but does take a while especially when it’s cold weather but even when it’s not cold outside sometimes I can drive for 40-50 mins and it’s still not at 90 degrees , the needle on the temperature dial just hovers about 1/4 of the way round .
Whenever the temperature does decide to get to 90 as soon as I slow down the temperature quickly drops again and can take ages to get back to 90 degrees.

Anyone have any thoughts on what I should be getting checked?
All I can say is that my Coolant level has never dropped so I definitely have coolant in the van so I know I’m not leaking coolant. Apart from that any advice would be greatly appreciated.
User avatar
the swan fiend
Hyper Poster
Posts: 5118
Joined: Sat Feb 18, 2017 10:52 pm
Engine size/power: 1.6 CR TDI (102bhp)

Re: Engine not fully heating up

Post by the swan fiend »

My 1.6 is quite slow to get to temperature too, like you I’ve checked everything out and all seems well. I can sit at anything from 55 to 65 mph on the motorway for my 13 mile drive to work in anything from 4 degrees or so and cooler and it only gets up to 80 or 85 degrees.
The only thing that bothers me about it is I’m not sure the DPF will regenerate if it’s not upto the full 90 degrees, so I normally make sure I give it a faster run when it’s a bit warmer.


Sent from my iPhone using Tapatalk
Rescue me from the swans in me
BenT
100BHP+
Posts: 171
Joined: Fri Nov 19, 2021 9:26 pm
Engine size/power: 1.6 CR TDI (102bhp)

Re: Engine not fully heating up

Post by BenT »

Sounds like your thermostat's stuck open. Most of my TDIs have had this happen at some stage. They normally only cost a few pounds and take less than half an hour to do. That said, I've never done it on a 1.6 before and it's not the simplest under-bonnet! If one of the coolant hoses going to the radiator is warm/hot before the temperature display's got to 90 degrees this is very likely the problem.
User avatar
NZDubNurd
Hyper Poster
Posts: 642
Joined: Fri Oct 24, 2014 3:39 am
Location: Whangarei, New Zealand

Re: Engine not fully heating up

Post by NZDubNurd »

Yep. Thermostat issue. The gauge reads 90c once the engine gets to 75C, so if it's hovering under "90", then the engine is really only in the 60's or early 70's.

You can cheak the actual temp in VCDS, or on the Climatronic secret menu, if you have dual zone climatronic system.
User avatar
DeanWhit
Hyper Poster
Posts: 628
Joined: Tue Jul 23, 2019 4:41 pm
Engine size/power: 2.0 TDI (140bhp)
Location: Wigan

Re: Engine not fully heating up

Post by DeanWhit »

Glad you’ve posted this as mine is doing the exact same thing. Booking it in at the garage on a Monday.
Pinnacle100
Caddy Fan
Posts: 53
Joined: Sun Oct 15, 2017 8:51 pm

Re: Engine not fully heating up

Post by Pinnacle100 »

Thank you all for your replies.
I had a look at some videos on changing the thermostat but it looks a bit out of my comfort zone so I’ll need to get it into the friendly local mechanic. DeanWhit please let us know how you get on with yours .
samyam1
Caddy2k Groupie
Posts: 34
Joined: Sat Nov 04, 2023 12:52 pm

Re: Engine not fully heating up

Post by samyam1 »

Sounds like my issue too.

Get up to 90 but if you stop with the engine running it drops down again. Going to be a job for this week whilst it’s quiet at work.


Sent from my iPhone using Tapatalk
User avatar
DeanWhit
Hyper Poster
Posts: 628
Joined: Tue Jul 23, 2019 4:41 pm
Engine size/power: 2.0 TDI (140bhp)
Location: Wigan

Re: Engine not fully heating up

Post by DeanWhit »

Update!!

Had at least one of the coolant temperature sensors changed on Friday. Just been out on the motorway and a bit of driving around town and it’s doing the same thing. Temp gauge barely got up to half way.
Any ideas?

The heaters aren’t particularly blowing hot, just warm really.
Dave_c85
Caddy2k Groupie
Posts: 36
Joined: Thu Feb 20, 2020 11:42 pm
Engine size/power: 1.6 CR TDI (102bhp)

Re: Engine not fully heating up

Post by Dave_c85 »

Sounds like the stat is stuck open. Had this on mine a while back, pretty hard to access so labour charges were significant!

If you turn the heaters on max heat and max flow and the temp drops it's a good indicator of stat stuck open.
User avatar
DeanWhit
Hyper Poster
Posts: 628
Joined: Tue Jul 23, 2019 4:41 pm
Engine size/power: 2.0 TDI (140bhp)
Location: Wigan

Re: Engine not fully heating up

Post by DeanWhit »

Is the ‘stat’ something different to the coolant temperature sensor that I’ve just had changed?
Dave_c85
Caddy2k Groupie
Posts: 36
Joined: Thu Feb 20, 2020 11:42 pm
Engine size/power: 1.6 CR TDI (102bhp)

Re: Engine not fully heating up

Post by Dave_c85 »

DeanWhit wrote: Sun Jan 07, 2024 5:25 pm Is the ‘stat’ something different to the coolant temperature sensor that I’ve just had changed?
Yep, thermostat will open and close to bring the radiator in and out of circuit. It's closed when engine is cool and once engine gets up to temp it opens to send the coolant through the radiator. It'll then open and close as needed to keep engine temp in check. If it's stuck open it's always sending coolant to the radiator so in effect over cooling the engine (better than being stuck closed which would cause overheating), hence why your temp on dash is low. The temperature sensor just reads coolant temperature.
User avatar
DeanWhit
Hyper Poster
Posts: 628
Joined: Tue Jul 23, 2019 4:41 pm
Engine size/power: 2.0 TDI (140bhp)
Location: Wigan

Re: Engine not fully heating up

Post by DeanWhit »

Brilliant, nice one.
PeterAFox
100BHP+
Posts: 179
Joined: Thu Aug 24, 2023 8:14 am
Engine size/power: 1.9 TDI (104bhp)

Re: Engine not fully heating up

Post by PeterAFox »

If you want to DIY:
here OEM thermostats sell for 12-15€ (at least for mine)
biggest hassle is that the coolant needs to be drained - for me this means axle stands and buckets.
Technically it's not difficult - the thing to really check is that the new thermostat is seated correctly with washer etc. before refilling the coolant
User avatar
DeanWhit
Hyper Poster
Posts: 628
Joined: Tue Jul 23, 2019 4:41 pm
Engine size/power: 2.0 TDI (140bhp)
Location: Wigan

Re: Engine not fully heating up

Post by DeanWhit »

Booked in for the 24th. I get the feeling it’s going to be an expensive one 😭
dangoesfast
Caddy2k Groupie
Posts: 9
Joined: Fri Jan 12, 2024 12:00 am
Engine size/power: 1.6 CR TDI (75bhp)

Re: Engine not fully heating up

Post by dangoesfast »

Thermostats are cheap and extremely easy to replace (apprentice work), if it's an expensive one then I'd look for another mechanic.
Post Reply