My 365BB is leaking coolant. I expected to find the water pump shaft seal leaking but that appears to be fine. Looking closely underneath I find a moist patch on the sheet steel right at the rear of the tunnel through which the coolant pipes head off to the radiator. What are the tips and tricks to get a look at what’s going on in that tunnel? I’ve not found any really informative drawing, diagram or photo to guide me in gaining access. Anyone been there and care to point me the way to go? Thanks in advance.
The two aluminium pipes that run through the tunnel tend to corrode my guess is that these need replacing. You need to have the engine out to get the pipes out (just disconnect them from the hoses at the front and pull them out backwards), but I guess the engine is out if you looked at the water pump seal. When I changed mine I simply had new ones made by a specialist (Carbuilder.com in Kent, as I recall) Sent from my iPhone using FerrariChat.com mobile app
Hello Simon - thanks for replying. The engine is not out but from the isolated damp patch away from the engine I’ve assumed the leak is not from the pump seal, which initially I thought most likely. The engine will soon come out for a belt change, so perhaps this is a good time to have spotted the coolant leak. Terry
Simon - were new pipes made in aluminium or thin wall stainless? Stainless might be an improvement but the aluminium has lasted over 45 years. Terry
I remade mine in aluminium in 2006 and they are still 100% as far as I know. I sold 365BB in 2019 but know the new owner. I suggest you just wait until the engine is out for the belts (and tensioner/water pump seal/camshaft seals etc) and take the pipes out and inspect them. Sent from my iPhone using FerrariChat.com mobile app
I see that Superformance have one of these at £150 and Maranello at £220, both in stainless. I think I had mine made for a lot less than this Sent from my iPhone using FerrariChat.com mobile app
I saw those parts too and I think there are local fabricators who can do a more cost effective job. It's an odd fault in the sense that it leaks - but not all the time. Topped it up today and underneath is, in between times, bone dry.
Good day TerryG, Although you did not mention it... but I would double check and tighten all of the various hose clamps especially those from the top left of the engine around the water pump. Any small leak can follow the tube to its lowest portion which is close to where you are describing. If all looks fine, then pressure test the cooling system, as this will or will not reveal the leak. If the pressure test holds pressure then it could be that the system is releasing pressure and coolant via the overflow hose/tube which allows coolant to flow to the area you mentioned? Just a few thoughts. Cheers, Sam
Hello Sam Thanks for those very sensible suggestions. As you can imagine, I’ve wanted to find a more easily rectified solution and have drawn a blank so far. I will check again, including a pressure test, which I’ve not done so far. Terry
Good day Terry, You are most welcome! A few more items I just thought of: a. Ensure to check/pressure test the expansion tank cap as well. If the cap is not holding pressure then it would prematurely allow coolant to escape which could find its way to the area you mentioned. b. As part of the cooling system pressure test, really examine the expansion tank. Over time the tank can rust from the inside (usually the very bottom) creating pin holes that would allow coolant to escape. I had this happen on my car and at the time there were no replacements available and so I had it repaired. It worked fine, but I wanted a new one and so I replaced it when one became available. Speaking of which, if you or anyone replaces the expansion tank double check the overall height, as the new replacement tanks appear to sit taller (the tank legs are longer) which can contact the rear clam when you are closing it and potentially causing damage. Cheers, Sam
Make sure the hose clamps at the front of the pipes below the rack are okay too. The coolant can run from the front to the rear and drip out. Changing the central pipes will be very unpleasant.
Paul - thanks for the warning and the pointer to the front clamps. Sam - Paul’s comment on difficulty of replacement of the tubes in the central tunnel certainly makes it necessary to check everything else per your advice before accepting it’s got to be done. The header tank was replaced about 8 years ago, with a 328 (I think) tank that was modified. That was before the car came to me. It’s still worth checking though.
A brief update, although the jury is still out. I went round the engine once again and all was dry there. Looking underneath there was the damp patch at the rear of the tunnel and, when I removed the front inspection cover there was more damp, more than at the rear. Feeling around the hoses at the front drew a blank as far as I could see and feel. I pressurised the system and there was no visible change in leak rate over an hour or so. As a precaution I tightened the front hose clamps just a little. That was a week ago and since then I don’t see any coolant on the floor! I’ll get it on the lift again soon. I may be on borrowed time with those centre pipes running through the tunnel. Thanks again for the tips and pointers.
until now I never had a leaking pipe in the center tunnel. most the clamps are not tighten or the short hoses are broken because of the age. but good just now no leak and the system holds the pressure
