[trevtherevs]

I was hoping for some advice from members regarding changing the coolant hoses on my 2003 mgtf. I am looking to drop the engine out as soon as the weather becomes a bit warmer. Whilst I have the subframe etc out I intend to replace the clutch and gearbox seals and thought it might be realistic to replace whatever else is more accessible. Whilst I'm a great advocate of if it's not broke don't fix it, I also know things don't last forever.
I am at a crossroads of if I start renewing hoses that are in difficult to reach positions when the engine is back in place, will this then stress those old hoses that I didn't replace? So is it replace all the hoses or only any that look week and worn?

 

[98luke]

I can understand your concern and my preventative nature would suggest replacing with new. However, as to whether replacing some hoses places more stress on the older hoses, there is a possibility of this happening given that the older hoses may be more compliant and more likely to expand under a given pressure. If you replace some of the hoses in the system that are new and therefore less compliant, there is likely to be more stress on the older hoses forcing them to expand further and possibly burst. Ultimately the vent pressure is determined by the reservoir cap and it may be a good idea to replace that at the same time.

 

[trevtherevs]

Hi, thanks for your reply. Yes, I did wonder if any of the old hoses I leave would compromise the system by being the weakest link. I also understand by reading previous posts that sometimes the replacement hose can not be as sturdy as those fitted when new, so all in all a bit of a head-scratcher.
I hadn't thought of the reservoir cap but I think it's a great suggestion which I will now certainly replace.

 

[mowog73]

I'm not sure if it would compromise old hoses because the operating pressure of the system stays the same, whether you changes hoses or not, the the operating conditions the old hoses see is going to be the same, whether the hoses around it have been renewed or not.

I renewed may coolant hoses in my F about 8 years ago and none of the old, possibly original hoses have failed due to replacing some some hoses. That being said, I'm going to check the older hoses on my car this winter.

 

[Robertf]

I agree with mowog73 concerning the pressure on old and new coolant hoses. Currently in the process of changing all my hoses and not seeing any ill effects as I work through them. (not changing all at the same time, but in stages).

 

[trevtherevs]

Thanks, Robertf and mogog73 for your thoughts on the renewal of the coolant hoses. I agree that thinking about it, whilst the hose might be new, the pressure in the system is the same. As long as the hose is not damaged in any way it should be serviceable.
It is a pricey adventure to replace all the hoses and whilst a hose failure can also be expensive, in the long run, I think I will replace those which are easiest to replace with the engine subframe out and work around the others periodically.

 

[dert]

Only pipes I've ever seen fail engne bay wise on the F and TF are the metal coolant pipes which go to the waterpump and the F/early TF heater inlet/outlet circled in red in the picture and the coolant bottle pipe feeding to the engine, all other never had a problem with.

 

[trevtherevs]

I was told some of those pipes you indicate have a knack of rubbing and going thin. When changing the under-floor pipes a couple of years ago I was told by the garage to check the rear engine metal pipes as can be dodgy. I know stainless is available but I couldn't see any external wear at the time. In fact they looked like new but thought when engine is out Id give closer inspection.

 

[mowog73]

I have found a couple of hoses that were rubbing against something and I put a piece of material around it to stop the rubbing (and replaced if necessary).

The engine coolant rail, the one behind the engine, #62 in the picture, was in very bad condition on my wife's F. I couldn't tell how bad it was until I was under the car looking up at it, and then I saw how really bad it was. I replaced it with the SS version. The first two pictures are from underneath, no coolant was visible from above.

 

[trevtherevs]

Thanks again for your advice and the great picturesI will have a much better check of the coolant rail when I have the engine out and if needed will replace it with a stainless replacement. I always had some worry about the rail when I changed the underfloor pipes, but I had read they were not a significant problem, but knowing my track record with luck and the garage saying to keep an eye I have to admit I did get a bit paranoid.

 

[mowog73]

I should add that that same pipe on my F, which is 3 months newer than my wife's F (mine was built in Dec 1995), looks fine.

 

[Daveyboyz]

I did the lot sometime ago with a roose silicone hose kit, I am told these last a long time. It was a bit of a nightmare job though especially because Rimmers sold me a faulty PRT thermostat and I couldn't work out why it was overheating.

In actual fact the only pipe I didn't replace was the metal coolant rail pictured above. If memory serves someone was doing them in stainless steel weren't they?