I bought a water pump from them and it was used pos. In a new box. Use caution.
I've been examining a failed heat exchanger sent in by a fellow fchatter and it appears that the problematic side is from the oil and not the coolant, at least in this case. Here's what one of the leaky tubes looked like after removal and cleaning up. The part that was leaking was near the end and was destroyed in the removal process. I have a new tube above for comparison. The outer tube is corroded to the point of being completely gone. That's why it leaked. The tube just corroded away. Measurements: Old: 5.5-5.7mm OD ~5.0mm ID walls: 0.25-0.35mm New: 6.3mm OD 4.7mm ID walls: 0.8mm (I guessed at the new material based on what sticks out of the HE) Image Unavailable, Please Login Here's an end view. Note how thin the walls of the tube are. The inside of this tube is cruddy because it has a leak but the ones without a leak were pristine on the inside with no apparent wear or corrosion. I think blaming heat exchanger failure on a lack of coolant changes may be misguided. Image Unavailable, Please Login I can conclude that in this case, the oil side of the HE was the one that caused the failure. There does appear to be some slight erosion of the inner tubes but they are still shiny so it's very slight. The outer tube is obviously corroded or eroded. They're rough, have a varied surface, and the wall thickness varies quite a bit. The tubes are made of copper. The housing for the HE is made from brass and it appears that the ends that hold the tubes are brass as well. Brass is a harder metal than copper and less subject to corrosion or erosion. The copper alloy they used appears to be very soft. It was extremely easy to machine out the tube without generating heat. From this cursory investigation, I would conclude that the reason why the 360 heat exchanger is failing is because the oil used in this vehicle is corrosive to copper. It could be that people who used oil that isn't corrosive to copper have pristine heat exchangers. I doubt that oil by itself is erosive to copper. Oil by its very nature is unlikely to erode anything. This tube was from an area away from the ports so didn't have a direct flow. If erosion was the issue, I'd expect the tubes in the direct flow of the input port to be the ones that failed first. Another conclusion I can draw is that repairing this particular heat exchanger would be time consuming. Every tube would have to be replaced and there are a 61 of them. The process is simple and it can be done quickly if all the tubes are coming out. Once the drill press is set up, it's just a matter of point and shoot. The difficulty is strictly in the labor. It looks the brass part of the HE is unaffected so the basic unit can be repaired if one goes through the trouble of removing and replacing all 61 tubes. All tubes have to be replaced or there's no point in repairing the unit. A more in-depth version of this post is available on my blog: https://www.ferrari360.org/2023/10/ferrari-360-heat-exchanger-failure.html
Another impressive post. Thanks for the very analytical post and post mortem analysis. So in the words of my favorite lecturers In our experience (ie n=1) In our series (ie n=2) In our study (ie n=3) Looks like good preliminary info. need to increase the n. So what is needed is more failed heat exchanger donors Which type of gear oil would be corrosive to copper? I remember a thread on 4 vs 5 gear oil . I’ll look it up. -ray
Here is the thread 360 f1 gearbox oil https://www.ferrarichat.com/forum/index.php?threads/360-f1-gearbox-oil.551557/
I was wondering if the link between destroyed syncros and failed heat exchangers isn't that the heat exchanger failed and the mix of coolant and oil destroyed the syncros. The link is probably the oil itself. If the oil is not copper safe, then it will corrode both those components until one of them fails. I would love to have a couple more samples so a real conclusion could be formed. With n=1, I have a theory with some proof but nothing conclusive that could be applied to the fleet.
So it might be a good idea to do an oil analysis every oil change and if you see an uptick in copper in the oil one might want to replace the heat exchange?
That F1 gearbox thread makes my head implode. LOL. never thought it'd be so hard to know what fluid to use! Currently, I'm with Ravenol VSG.
The recommended gear oil which is the Shell product is both GL4 and GL5 specs. I wonder if there is a correlation between failure and use of non-OEM recommended gear oil which does not also have the GL4 rating?.
This is post #11 from that gear oil thread: may be the most relevant post for this issue in that thread. 360 f1 gearbox oil https://www.ferrarichat.com/forum/index.php?posts/145361371/
Looks like the Red Line MT-90 75W-90 (GL4 1A Light Orange) is the only one on that list that's the least corrosive. Lots of room for error with that list of oils. I'm pretty sure that choosing the wrong oil can really spoil your day, week, and month. The result of the corrosion is a sand like material that probably would end up in the transaxle filter screen. If you pull your filter screen and it's got a lot of sand like particles, it's likely your oil is eating your syncros and heat exchanger. The metal from those parts is in your filter. I'd recommend that anyone who is not sure of what oil is in their transaxle to have it replaced ASAP with an oil that's benign to copper and brass.
I can get another leaky exchanger dismantled and see the real culprit, just like what you did but ,how to remove the tube?
I did a quick analysis of the cost to build a heat exchanger from scratch and it's over $300 in materials alone. Add in the labor and overhead and it's a $500+ part to manufacture. @24000rpm - I used a tapered reamer to release the tube and an awl to push it out. It came out pretty easily. I used WD-40 to clean it up.
It seems to me that the solution to this heat exchanger problem is to make the thing out of aluminum instead of brass and copper. Sure, the heat index for aluminum isn't as good as copper or brass but the difference is slight and an aluminum heat exchanger should last literally forever. Making one out of aluminum would be far less expensive but would be more complex since aluminum can't be easily soldered. Any thoughts why aluminum wouldn't be a great solution to this problem?
My opinion. So the first thing to verify is is the theory for all/most failures due to the oil side. Then perhaps choosing the oil that’s least corrosive to copper may be the best solution. How corrosive is the gear oil to aluminum, and how susceptible is the aluminum to the effects of coolant. Would you be trading one problem for another? -ray
Aluminum coolant radiators last forever so there must be zero issues with compatibility providing the coolant is serviced periodically. Aluminum oil radiators also last a long time with engine oil. But that is not saying much for gear oil which can be different.
I made a model of the heat exchanger to see what it would cost to print it directly instead of all the fiddling around with manufacturing. Image Unavailable, Please Login This is aluminum, specifically, AlSiMg. I think that pretty much puts that idea to bed. Aluminum should hold up well with any oil. Just think. The oil is circulating in an aluminum transaxle. If it was to corrode that, we'd have a LOT of larger issues.
GL4 is a very bad idea in a 360. It has a very small hypoid ring and pinion and need the anti wear properties of GL5.
If you research the differences in GL4 and GL5 you will understand it is sales hype. The needs of transmissions that use GL4 and differentials that use GL5 are at odds with each other. The needs of a syncro is served by the chemistry of GL4 (Called by the industry "Transmission oil") and it has to allow for friction that allows the syncros to work. GL5 chemistry (Called by the industry "Differential oil") is designed to reduce friction as much as possible inhibiting syncro action and causing shredding of brass particles from the syncro surface as it fights to wear through the anti friction layer the GL5 additives leave on metal surfaces to reduce friction. In my opinion from rebuilding so many 360 transaxles GL4 kills gears at a higher rate than GL5 kills syncros.
Thank you for your opinion. Does this also hold true for oils rated both GL4 and GL5? How could a product satisfy both of what seems like mutually excluding properties? Truth, hype, marketing BS?
I recall a few years ago a member with cavitation in a 360 head which caused a coolant leak into a cylinder. we presumed It was due to cavitation from corrosive effects of coolant combined with a particularly thin wall. I am neither a metallurgist nor a chemist. Here are a couple of sources that show the potential deleterious effects of ethylene glycol on aluminum. Just food for thought. Like I said I was just bring up a point that there may be a trade off if considering aluminum to replace the copper. You may be trading the oil side corrosion for coolant side corrosion. https://penray.com/resources/cooling-system-tech-facts/metal-corrosion/ https://www.hindawi.com/journals/ijc/2019/9020489/ As far as comparing the thick gearbox casing to these gracile tubes may not be an adequate comparison. Over the course of 20 years if you lose a few mils in each, the sequela from corrosion of a tube will clearly cause more of an issue. I have no idea if gear oil is corrosive to aluminum. Just something to consider before venturing into this. -ray
