Thermostat / hose query - 2014 E350 CDI convertible

[FarnhamMB]

Hi all, Hope someone can help!

Last week I bought my first MB (Had BMWs all my life), and sorting out a couple of issues. Already replaced the battery, oil filter/cabin filter/ oil/ cabin filter. Next job is a garage for transmission service.

Anyway, engine temp was very erratic, sometimes would go up but would often sit at 40, so I'm thinking thermostat. I order one in and start the job. Hit two snags.

Firstly (most importantly), I've managed to snap a plastic hose connector (see pic below). Its a T hose that is part of the coolant system. Its no ordinary connector, has no jubilee clip or anything. It seems to be just a push fit..... but the hardest push fit on the planet. no amount of pliers or anything can seem to get this small hose of the T connector. Does anyone know a way around this? My only thoughts are a new connector, then cut each of the hoses down by 10mm and fix it on again, perhaps with a jubilee. On that, I've no idea what the T connector is called, is there a source for exploded diagrams of engines so I can call MB up and order?

Secondly, the current thermostat has a electrical connector. The new housing has space for the connector, but no connector. Would anyone know if you can just swap the thermostat its self, and use the old housing?

Many thanks in advance!

Andrew

(ps -if anyone lives around Farnham / Guildford way and can recommend a good Indy then I'm all ears.)

 

[AndrewOl]

Hi Andrew and welcome. Problems with the thermostat on these engines is common and they tend to open early causing the engine to run cool, especially in winter. I can’t really see where the broken bit is but it looks like it may have been leaking by the state of the hose next to it. PCS in horndean come highly recommended. I use Pentangle near Southampton. Sounds like you may have the wrong thermostat, it would be better to swap for the right one as they are horribly expensive to start messing about with. If you can take a picture a bit further out so I can get my bearings then I can have a look on the EPC for some clues as to what it is that I’d broken.

 

[FarnhamMB]

Hi, thanks for your reply.

After some research it seems its the fuel return pipe t-section..... And it seems impossible to replace the tiny t-section and you need to spend £100 on the whole set of pipes that leads to the injectors and is a 3hr labour job to do! Pretty sure I could cry!

I've ordered the pipe but I now wonder if I'm able to drive 20 mins to the garage to repair the fuel return with the pipe not connected!?

Re the thermostat I'll open it up and see if I can repair the old one but as you say, I think I'll get a new one. Frustrating as auto doc said it was the right part, and same OE number!

 

[MrGreedy]

The recommendation is to buy a genuine Merc part, which is made by Wahler, as these cars can be very sensitive.

You do need a replacement with an electrical connector. This is for a small 40mm long 'knitting needle-like' immersion heater down the centre of the sprung thermostat, which has the effect of being able to fine tune thermostat opening.

The consequence of this and the very tight tolerance between immersion heater and the small hole for it down the centre of the thermostat is that small amounts of scale/oxide can foul the hole, which inhibits the sliding of the sprung thermostat.

The traditional £10 sprung thermostat part can be separated from the body, and some people have had success changing this part, sourced from Autodoc.

Some people have had success removing the sprung thermostat part, and careful/gently cleaned or chemically cleaned the immersion 'needle' and the receiving hole in the sprung thermostat.

If you don't buy a new thermostat, you will need a new thermostat gasket. Genuine Merc ones are now £22 and hard to get. There are aftermarket available via Autodoc, but days shipping.

Some other recent threads on this forum:

Om642 Thermostat | Engine

I fear I know the answer to this but do I honestly need to spend over £150 for a thermostat? There is nothing wrong with the housing and actual valve is just a standard type of unit. There seems to be limited availability too, is there an issue with these valves as they seem to be a common point...

forums.mbclub.co.uk

E350 CDI OM642 slight temp fluctuation very cold weather | Engine

Good day all, I know normally when people's cars aren't getting up to temp, the first place to look is the thermostat being on the way out. The shift I'm about to explain is relatively minor, and not the 'struggles to get above 65°C' that we often get asked about. Given that it's freezing...

forums.mbclub.co.uk

 

[W1ghty]

@Jobsworth is a specialist in your area I believe (he will see this mention)
Ian at Star Mercedes specialist near Reading

 

[DSM10000]

Was the car purchased privately or through a dealer?

It seems to be needing a lot of routine service work carried out.

 

[FarnhamMB]

Thanks MrGreedy. Very helpful links and videos in there. I think I'll order a new one off Autodoc (with connector) I called the local MB indy garage which comes recommended, and was quoted £400 (inc VAT) for new thermostat+fitting. It's the 'easy' change on the top (no belt removal).... seemed on the steep side! (for comparison, the transmission service was £240 inc VAT which seemed reasonable.

Andrew