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FourDoor

1.3 mh thermostat and housing sealing

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FourDoor

Just made an account to ask this question as I thought it’d be the best place to ask! Possibly a slightly daft question...

 

For any experts on the older engines. I have an 86 1.3 mh block golf (not a polo I know but I’ve been told this is the best spot for 1.3 info)  chased down overheating issues to leaking and warped thermostat housing/ cover/ elbow thing. 

 

Installed a new housing elbow which is quickly warping again and going back to the shape of the one that wouldn’t seal right.

 

just to make sure I’ve got the right gear for the job which thermostat and seal should I be using? I’ve seen some which have a seal around the edge of the thermostat that look like they have a groove that the outer edge of the thermostat sits in. And I’ve seen some that say to just use the o ring on the thermostat housing with none for the ‘stat itself. 

 

Reasonsbly new to this so any help would be appreciated!

 

 

 

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dvderlm

Welcome.  You've come to the right 1.3 place.

 

Did you change the thermostat, or just the elbow?

 

If the thermostat is sticking closed coolant won't flow around the major circuit which includes the radiator,

only around the minor circuit which includes the car interior heater.

 

Replacement thermostats from reputable brands often but not always come with an o-ring.

 

There are 2 o-rings for MH engine. 

 

See the parts diagram here for part numbers 3 and 5.

https://volkswagen.7zap.com/en/rdw/polo+derby+vento-ind/po/1986-9/1/121-8060/

The thermostat valve is termed "coolant regulator" on that page - I suspect translated from Russian or German.

 

(Is the plastic housing itself warped from heat? My thermostat housing is metal)

Edited by dvderlm

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FourDoor

Thanks mate! 

Ive changed the thermostat and elbow, the issue im Having is mainly just the plastic elbow warping, I believe only certain early ones came with the metal elbow?

 

I believe the way the previous owner had installed the thermostat had mislead me when I re installed my new one so there was too much pressure under the housing when clamped down by the bolts. The way it was set up when I got it was- o ring then thermostat then housing with another o ring. Looking like there’s been an extra seal added in the mix at some point.

 

just for reference I’ve done the head gasket, water pump, belt, reservoir/ cap, radiator and fan switches and sensors, overheating has gone down and fan cycles, vdo gauge is showing 90 degrees when lower hose starts to get hot which says to me new thermostat is working fine. O ring number 5 on the diagram is in place and no leaking there.

 

bit long winded but can’t go on with them warping at this rate!

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dvderlm

The o-ring is 50x4 so 4mm cross section, two of those would give quite a thin overlap for the elbow in housing, a bit like closing the lid on an overpacked suitcase.

 

Actually the elbow on mine is plastic too now, just the housing changed around 85 - maybe the hole in the block too.

When I replaced my elbow (it was damaged on a posted head) it took ages to find the right one and there were big quality variations in the parts I received

until I found correct sized and angled part for old metal housing.

 

Things like no brass inserts for the bolts or lack of reinforcements in the moulding.

I'd trust Febi or Berth parts. eg Febi 23346.

 

I wonder if the bottom hose is correct part. It needs to flex as engine rocks. Gates 3555 on the Polo, I assume rad to engine is same distance on the Golf?

no hose part number here

https://volkswagen.7zap.com/en/rdw/golf/go/1986-64/1/121-21000/

 

Found it 

https://volkswagen.7zap.com/en/rdw/golf/go/1986-64/1/121-17050/

part 1.

030121056g

longer than the Gates part for Polo and loads of other makes, probably Topran 109196.

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FourDoor

I’ll give it a go with a new elbow and one o ring tomorrow and see how it goes, I’d imagine it be fine as that’s how every diagram I’ve seen shows it. The housing I’ve got has all threaded inserts and reinforcement, seen some that use self tappers for the elbow which seems a bit cheap. Thanks for the info mate 

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steveo3002

in some way the self tapers are better , as once the screws corrode in the insert type it can spin the insert out when you unscrew the bolts next time

 

  • Thanks 1

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