What is causing our cab floor to leak?
QMy 2004 Auto-Trail motorhome with a 2.8-litre diesel engine has sprung a leak in the cab on the passenger side where the passenger’s feet would be.
About four weeks ago I started the engine and moved the vehicle up and down my driveway (it is SORNed) to circulate the tyre positions. I ran the vehicle for nearly an hour to get it nice and warm and had the heater selected to position two in order to bring some heat into the cab.
So, it’s now been standing idle for four weeks and doing a check around the motorhome I have found a wet carpet in the passenger footwell and a small puddle that shows it is an antifreeze mixture. In the engine bay, the water in the header tank has dropped noticeably to the lower limit level.
Where is this water coming from and how can I repair it? Peter Ward
AI am afraid to say that there is no doubt about it – you do have a leak from your heat exchanger, or matrix as it is often referred to.
Adding some Radweld or Bars-Leaks can sometimes help to reduce a minor leak enough to get you home, but it will not solve the problem and it will get worse.
Breathing in the fumes from hot engine coolant is not healthy and the windscreen will steam up, too, so it is going to need to be replaced.
There is no sugar-coating this – it is a horrible job. The heater box has to be removed and this entails removing the entire dashboard and steering column. There are hundreds of screws to remove and it cannot be rushed.
We did many of these in our workshops and, even with experience, we could not get it done in an eight-hour day. It takes around 10 to 12 hours of skin-stripping, backstretching, painstaking patience.
While you can get a pattern heater unit from aftermarket sources, these have been found to be of varying quality so, if there is a Fiat genuine item available, I would insist on that. It will come ready to fit, while some non-original items require you to fit the plastic connections yourself, which just introduces another element of risk of leaking and having to do it again. You definitely won’t want to have this done twice!
I would also advise that you need to get this done by a reputable garage that will guarantee its work and has done such things before.
Nick Fisher