Oil Cooler Pipe Replacement
I have to admit to a degree of paranoia being the driving force behind this activity. I like to think that I can leap into my Mk1 with 143,000 miles on board, and drive three hundred miles at high speed with out breakdown and of all the many possible things that could go wrong, the failure of these pipes has to figure quite strongly in the equation of unreliability. Some postings on the MR2 Drivers club site , indicate that engines have been wrecked by these components bursting or maybe just coming undone. Any way its clear that at very least careful inspection is required, and given that to do this properly you have to remove the underside engine cover panel, you may as well go the whole hog and change out the pipes if you have an extended mileage vehicle.
First step is to buy some replacement hose. In my part of the world the usual car accessory shops don't stock high temperature oil hose but specialist racing suppliers should be able to help. I purchased a metre of stainless steel reinforced hose for about £10.00 from Formula 1 Racing at Brands Hatch (01 474 852271). This was more than sufficient to make up the two pipes required. Cutting it was a bit of a pain but a fine bladed hack saw did the trick aided by some final tidying up with wire cutters.
New Pipes Ends of
Having jacked the car up and positioned axel stands in the right place, removing the under side trim will reveal the oil cooler pipes in all their glory. This is a job best done with a cold engine. It isn't necessary to drain the oil as the connections are at a higher level than the sump contents, but you should be prepared for leakage from the oil cooler itself. For those that haven't investigated this area before, the oil "cooler" is actually a sleeve around the main water feed to the radiator. It cant be the most efficient system but I guess it works.
To undo the 10mm bolts on the hose clips you will probably need a small ratchet tool for at least two of the bolts. It is probable that even with the clamps loosened, the pipes will be reluctant to shift but gripping the pipe with a wrench and twisting slightly should effect a release. Oil will certainly be present in the cooler assembly and if you have ready some blocking stubs, as used and pictured in the Fast Idle Fix (Section 1 of Tech Zone), one of these will prevent the "oil up the sleeve" phenomena.
Having removed the two pipes, a good clean up in petrol or detergent is maybe an idea. You will need to get them apart to remove the rubber reinforcing sleeve and heat shielding and a condition check might convince you that you aren't wasting your time.
The original pipes consisted of a nylon reinforced rubber inner, over which is slid a reinforcing rubber pipe which in turn is covered by a heat shielding aluminium sleeve. On my car only one pipe had this heat shield. I would appreciate feedback from other owners as to whether this is the norm. I could not see any signs of deterioration but it is impossible to see any cracks in the pipe under the nylon sleeving so replacement has to be the best policy.
From the same source as the new pipes, I purchased some thermo-flex heat shielding and using the original rubber sleeves over the new piping, made up the new assemblies with new heat shielding over both. New clips were fitted at the same time; the originals looked to be OK, but why take a chance for pennies.
Re-assembly is fairly easy, but the new pipes took a bit of effort to get on to the connectors. Apply oil to the inner pipe surfaces to make the task easier.
Double check the tightness of all the connections and do make sure you have slid the new pipes over the connecting stubs by at least 1.5 cm's before tightening the clips.
Whilst the car was jacked up, I took the opportunity of changing the gear box oil. The old oil came out like orange water. I have no idea how long it had been in service, but I am convinced that the gear box is now smoother especially when really hot.
More "peace of mind" for those long journeys!
i