Stainless Coolant pipes

[MAXTHEDOG]

Apologies in advance for a possible dumb question.
As I’m new to MGF/TF’s and I’m about to embark on checking and driving some, well as soon as the wind and rain have moved on. I wondered if the underbody coolant pipes are claimed to have been replaced with stainless it’s easy to tell. Do they retain their shiny appearance? I’m assuming steel ones will be the usual colour of rust.
Cheers,
Michael.

[seasider]

Rest assured that's a very valid question! Most cars will have had their underside pipes replaced by now (either as a precaution or due to a leak) although there will still be some on the originals. It should be possible to tell the difference though, as the originals would most likely look crusty (with surface rust) while stainless pipes should look smooth and certainly more shiny. If you get the chance to get a prospective car in the air then that should help. It will also help check for signs of corrosion, especially the front and rear subframes.

[MAXTHEDOG]

Thanks for your reply, Seasider.
There was one quite near I was going to go and see but it’s gone. Pity, as it came with a hardtop.
Regards,
Michael.

[Chris Tideswell]

My TF's pipes were changed 13 years ago and they still look new unlike the 7 year old originals. Having said that the original pipes tend to go from the inside out, mine looked OK until the chap doing the service prodded his finger through the pipe!

[Geoff.F]

Original - Magnetic
SS - Not Magnetic
Geoff. F

[seasider]

Original - Magnetic
SS - Not Magnetic
Geoff. F

SS can be magnetic as explained here:
https://www.metalsupermarkets.co.uk/is- ... -magnetic/
The higher the SS quality the lower the level of magnetism.
I don't think it's clear cut.

[RobboMC]

Also look at the hose clamps, if it's still got the awful OEM hose clamps the pipes may be original.

With the magnetism bit, I think if it's non-magnetic then it's stainless 304 but if it's magnetic it could still be stainless 400 series
which is usually used for mufflers and exhausts. So I'm guessing there's quite a few examples of magnetic stainless pipe out there.

[mowog73]

Also look at the hose clamps, if it's still got the awful OEM hose clamps the pipes may be original.

I can't agree at all with that statement, the OEM clamps are excellent. You never have to worry about the constant tension hose clamps that the OEMs use being too tight or not tight enough. And the constant tension hose clamp will keep constant tension on the pipe even if if you replace the original mild steel pipes with stainless steel pipes, which expands greater with temperature.

On both of our Fs, when I swapped out the original mild steel pipes for stainless steel pipes, I would find puddles of coolant under the car a few weeks after changing the pipes, and the same coolant puddles appeared after replacing coolant hoses, not because I can't tight a jubilee clamp sufficiently, no, it was due to the greater thermal expansion of stainless steel compared to mild steel. After a number of heating cycles, the jubilee clamp would become loose enough to allow a small amount of coolant to leak from the joint between the hose and the pipe and I would have to go under the car and tighten the jubilee clamp. I am now in the process of binning all the jubilee clamps and replacing them with the OEM constant tension hose clamps.

[RobboMC]

Ahh so much from a single word, awful.

I was referring mostly to the wresting match I generally have in removing such OEM clamps, not to the sealing or leakage;
but you raise an important point.

I have refitted new standard steel pipes so am having no issues with sealing BUT

there are 2 possibilities for the material in 'stainless' pipes.
High quality pipes should be 304 which has a thermal expansion up the high end of the 'range' usually offered for stainless around 17.

Pipes made from muffler grade pipe might well have a expansions closer to carbon steel of 10 or 11.

https://www.industrialmetalsupply.com/b ... 20%C2%B0C).



Your experience seems to raise the question: is it good to fit jubilee clamps to 304 stainless pipes

And the data suggests that the correct answer is NO!

Binning the jubilee clamps means draining the coolant again? Ouch!

[mowog73]

Ahh so much from a single word, awful.

I was referring mostly to the wresting match I generally have in removing such OEM clamps, not to the sealing or leakage;
but you raise an important point.

I will certainly agree with you there. The locally available specialty hose clamp plies are of fair quality, just marginally up to the task...just. The cable type hose clamps are helpful when trying to get to some of the clamps that would not be otherwise easily assessible. They won't lock at maximum open position, but when you grasp the handle, they do fully open the hose clamp, which allows you get them the clamp on/of the hose.

The hand-held hose clamp pliers are too flimsy and won't hold the hose clamp fully open, getting the clamp on/off some hoses is next to impossible. In those cases, I've resorted to using my name-brand Channellock adjustable pliers. The jaws' teeth work really well to grasp the hose clamp.