NB Thermostat housing pipe repair or replacement

  1. My model of MX-5 is: 1999 1.8 NB
  2. I’m based near: South Essex
  3. I’m looking for technical help or recommendations on: Thermostat Housing repair or replacement.

Hi all,
a couple of questions?
Q1. Is the thermostat housing the bit that bolts to the engine only accessible with the removal the timing belt etc? Just so you are aware, I have just replaced the timing belt and I could do with out taking it all off again :frowning:
Q2. is it possible to replace just the T piece of pipe that comes out from it, if so, what’s the best option?



The thermostat housing is removable without disturbing anything. Are you meaning the water pump?

Hi, no, not the water pump, as I have just replaced that whilst doing the timing belt, this is the part that the thermostat sits in, before you put the “top” on, that has the pipe from the top of the radiator .
The housing has a small pipe from the side that is a “T” piece and is prone to rotting! 2 small pipes connect to it.
I don’t really want to take everything off again if I can help it, although I do know that everything should be easy to undo again!

You’ll need the timing belt off again to remove the thermostat housing. It bolted to the cylinder head behind the black metal plate behind the camshaft pulleys.

I’ve carefully swapped the metal pipes over from one housing to another with good success. They are a press fit, I put some loctite around the one that I pushed in. You can’t get the pipes separately from the housing though so I took some good condition ones from a used housing.

I’m thinking that the replacement pipe is the way I’m going to go, watch this space as they say :rofl:

Tap it out and use a hose tail connector

Hi, it is an option that I’m considering

Have you managed to solve the problem?
Do you still need help?

Hi, thanks, but all sorted 2 years ago and the car has since been sold

I’ve had this issue before. The thermostat housing is usually bolted to the engine, and you might have to remove the timing belt again to get to it, which is annoying. But sometimes, you can just replace the T piece of the pipe without taking everything apart. Think of it like fixing clogged drains. Sometimes, a simple fix works. Check if your car model allows for replacing just the T piece. Make sure to get a good quality part. Good luck!