Volkswagen Mark IV Forum banner
1 - 16 of 16 Posts

·
Registered
Joined
·
905 Posts
Discussion Starter · #1 · (Edited)
changed the title from changing hater matrix hose to changing thermostat housing to better reflect the topic

I am losing considerable abmount of coolant from my car. I can see big spillages on top of the gearbox spilling from various things connected to the thermostat housing.

I can see leaks from the heater matrix hoses, I can feel the leaks coming from under the connection point between the thermostat housing and thermostat housing flange. I've changed the rubber gasket but I still feel antifreeze there.

I would like to change the heater matrix hoses to eliminate the leaks top down now 1by 1 because it's hard to tell if there is also a leak lower down, or whether the antifreeze is dropping down from above.

The part number is 1J0 121 156 BF at around £50 new. Should I try my luck of a 2nd hand part for £15 off the bay. Or maybe even do spot repair on the bit that connects to the thermostat housing. Your thoughts would be appreciated.
 

·
Registered
Joined
·
10,893 Posts
Karim, how long are you going to keep the car? As I recall you had it for quite some time..
If you are going keep it for a year or so go used... if you want to keep it longer buy new. It should last another 20 years when new... or go all out and get silicone pipes for the engine.. that is if you can find them for your engine they are thicker and stronger so should last at least twice the time of ordinary oem pipes.
 

·
Registered
Joined
·
905 Posts
Discussion Starter · #4 ·
Most likely I will have it for another year. Then again I've said that for the last 3 years.

It's just more economical to keep an old car running than to buy a new one.

I was thinking of sourcing a cheaper pipe like this: https://www.autodoc.co.uk/meyle/727...oKcoCjdo3Wd_Rb2wDwui9Mk1uBFVHesxoClboQAvD_BwE

And getting a pip connection kit and basically fabricate the leaking bits and repair it that way. But that pipe and that connection kit could cost me a fair amount.

I would just buy new if it was around £30-£35.
 

·
Registered
Joined
·
457 Posts

·
Registered
Joined
·
905 Posts
Discussion Starter · #8 ·
I had a look under the bonnet again, while there is some whtness where the thermostat housing and heater matrix hose connect. I think this could just be inconsequental coolant loss. There are two points of leaks from the thermostat housing.

Where the flange for the theromstat is, and much bigger leak where the sensor is plugged into the thermostat housing.

TPS are selling the replacement part for a whopping £94. A cheap pattern part by topran is £30 ish. I've decided to go with the cheap option for now because I can't justify some £94 quid for a plastic housing for a car that's not going to be kept long term.
 

·
Registered
Joined
·
1,269 Posts
Cheaper unit is fine, but might be wise to keep your old temp sensor, if it's a genuine VW part. My cheap, aftermarket sensor leaked into the loom. The thermostat was fine, but I replaced it for a Febi part as the car was becoming slower to get up to temp.
 

·
Registered
Joined
·
905 Posts
Discussion Starter · #10 ·
Wow, what a job. One of the most fiddliest of jobs I've done and it's not finished. I should have researched this before starting out would have saved me a lot of grief and save me from having to do the job twice.

A few years back I had to changed the coolant reservoir because one of the plastic pipe connectors broke off. Plastic parts on the cooling system is a pretty serious issue, just imagine if a plastic part breaks off from the cooling system while on a smart motorway and you're 10 miles away from a services. Do you stop and pray that the "smart" motorway will close that lane or do you take a chance with the car and drive it to a services with no coolant?

I should have done the smart thing and changed all the plastic parts in the cooling system when I changed out the expansion tank. As it turns out the thermostat housing is rotten! Plasttic connector to the heater matrix hose just crumbled away as I was trying to take the pipe off.

There is another part a long tube that runs from the thermostat housing to the cambelt side of the engine which has deteroriated and needs replacing. You can see the end of the tube below, and an inset picture of what a new part look like.

I put the housing back together the way it was for now. I've order the new part, as soon as I receive the new part I'll put it together.

Automotive tire Asphalt Gas Engineering Machine
 

·
Registered
Joined
·
10,893 Posts
I dislike plastic parts used in the cooling systems... as at some point the plastic is done for and with it having to deal with boiling temperatures most of the time, it will all of a sudden give up when disturbed simply because it has perished.... nothing else to do than just replacing the parts... just be glad it's not a V6 or R32 engine as they are worse to work on (read even less space)

Just get the part and sort it out... there is no otherway of dealing with it.
 

·
Registered
Joined
·
1,269 Posts
I ended up leaving the long pipe in place when I did mine, just undid the clip at the housing. I agree though, plastic parts in the cooling system are just trouble waiting to happen, the heat cycles are just making it more and more brittle.

Also, side note, your gearbox mount looks like it's slid out of alignment under the bolts. Likely someone reused the old bolts. You may get some noise when turning left sharply, if the engine side mount is making metal-metal contact when the engine moves about as you go round the corner. There's meant to be around 1cm clearance on the driver's side, if you are planning on lining it up/replacing the bolts for new.
 

·
Registered
Joined
·
905 Posts
Discussion Starter · #13 ·
I ended up leaving the long pipe in place when I did mine, just undid the clip at the housing. I agree though, plastic parts in the cooling system are just trouble waiting to happen, the heat cycles are just making it more and more brittle.

Also, side note, your gearbox mount looks like it's slid out of alignment under the bolts. Likely someone reused the old bolts. You may get some noise when turning left sharply, if the engine side mount is making metal-metal contact when the engine moves about as you go round the corner. There's meant to be around 1cm clearance on the driver's side, if you are planning on lining it up/replacing the bolts for new.
Thanks for the heads up with the gearbox mount.

I have no choice but to replace that tube. It's completely rotten as you can see in the pic there, it's not forming a water tight seal and I can see water dripping down fast from there.
 

·
Registered
Joined
·
1,269 Posts
Thanks for the heads up with the gearbox mount.

I have no choice but to replace that tube. It's completely rotten as you can see in the pic there, it's not forming a water tight seal and I can see water dripping down fast from there.
Just thinking, are you still having issues with 1st and 2nd gear? That could've been caused by the mount being out of alignment, especially since the linkage is a pinion and rod set up on the 1.6, and not the cable kind.

Have you managed to source a pipe? There's quite a few on eBay brand new for around £15-£20, if you haven't yet.
 

·
Registered
Joined
·
905 Posts
Discussion Starter · #15 · (Edited)
Just thinking, are you still having issues with 1st and 2nd gear? That could've been caused by the mount being out of alignment, especially since the linkage is a pinion and rod set up on the 1.6, and not the cable kind.

Have you managed to source a pipe? There's quite a few on eBay brand new for around £15-£20, if you haven't yet.
Still have intermittent issues with gears. I think it needs new gearbox mounts. The clutch was done a few years back and then a seperate clutch rod failed so the bolts were removed a few times.

I need the car fixed ASAP so I drove about 3 hours round trip to get it from a GSF car parts myself. The price is really good at £8 - so I the savings sort of paid for the fuel. code is 179VG1160 (COOLANT TUBE)

n.b. for anyone readying, the hole in the engine the pipe goes into might be full of burnt in crud in there, I couldn't get it out, it was stopping the pipe going in all the way. so I shaved off 2mm off the end of the coolant pipe to get it to fit Otherwise it's just a bit too long and stops the thermostat housing from lining up with the engine - if the housing doesnt line up it leaks.

The trimming shouldn't affect the performance what so ever, the rubber seal is completely intact, it's just that hard plastic lip is trimmed down by half its thickness (still enough meat left on it to be the seat of the rubber seal.
 
1 - 16 of 16 Posts
Top