I have just received a replacement DSG thermostat, after experiencing the dreaded slow engine warmup symptoms and dropping temperature gauge reading. I was due to replace the stat this weekend however, I'm now totally confused. Most posts indicate that the thermostat sticks in the open position, allowing full flow through the abs tube. I took the new thermostat out of its packaging to check any damage etc.

I noticed I could blow with ease though the unit. I then boiled the kettle and submerged the unit in hot water. the tubed then closed off, and restricted the flow through the unit.

1. So this unit cold, allows flow through it.

2. when the stat heats up, it closes off flow.

I dont want to fit this unit, only to find out it is faulty.

Many thanks of any advice

 

Hi, welcome.

 

I stay well away from DSG and diesels but others here know plenty about them and there will be posts and threads on the Yeti forum on DSG and general coolant issues.  If I've got it right, might not have, the part is a "coolant regulator"(?) or is that something else,(?), but it looks like a stat to me (and abs tube(?)), anyway, are you sure you've got this parts facing the correct way (arrow for flow direction) and instead of adding boiled water directly did you dilute with cold at it opens at 70c?.  Have look from about 1:40 on this video for testing old and new parts also see the end where he takes the old part, er, apart.

 

HTH.

 

ETA: wow, I got the name right, time to try the Lottery!.  https://www.lllparts.co.uk/product/1K0121113A/coolant-regulator

 

 

Edited 27 February27 Feb by nta16
ETA:

Hi,

Many thanks for the reply, yes I  have seen this video before,and it was best for information on testing a new unit with cold water, and stopping the flow through.And also the old unit not closing off. I can now confirm that my brand new  unit is faulty. It's stuck permanently in the open position allowing cold and hot water to pass through freely. I'm so glad I decided to test the unit,before going through the hassle of fitting, and then finding out,there's no change as to the slow warm-up of the engine.  And highly possible then doing the big job of main thermostat. Last night I stripped down the brand new unit. The brass thermostat has a small steel rod, and it was sticking out about 1/4inch. This was not allowing  the spring to force the stat body against the abs outlet inner flange and seal off any water flow. I then forced the steel rod back into thermostat, just to the point where in sits,and also causes a seal.

I put the unit back together,tested cold water and closed,hot water,it opens. I must have done the test at least 20-30 times,and it's now working as it should.

However, I'm still concernd it might fail again.I've been in touch with the supplier, explained as above,they apologised and are posting a replacement. So happy days.

Thanks

 

Sorry, I just noticed part of your advice,direction of flow etc. I never fitted it, that was planned to be done over this coming weekend. All I did was take it out of the box and tested it in advance.

Thanks for reporting back.

 

Be very careful with parts, there are lots of parts manufacturers some just put their label on the parts they get or are made by others, some parts are not so well made as others.  Some parts can be abysmal quality or not fully appropriate even if they say they are (particularly sensors for this).  Even good brands, or formerly good brands, can have a drop in quality from their former times.  Unfortunately it's a bit of a minefield, even VW labelled parts can be short lived blower resistor, front dampers come instantly to my mind.

 

It was a It was a very good idea of yours to check the part works.  Always a good idea to check the invoice and box before opening for correct part numbers or references, then the part in its packaging, then if possible test it works properly and fully, then if possible compare it to existing part (assuming that part is correct) and if possible whether the new part fits correctly (again assuming the existing part is fitted correctly).

 

Not only is it annoying to fit a new part for it to go faulty well before it's end of service life it can also be a great deal of time and hassle and large cost associated just with replacing the faulty part, I can assure you of this I've had it many times, same with faulty and/or poor quality work from the English motor trade.

 

Good luck, let us know how you get on.