Heat Exchanger Delete

Hi All
I’m reading and researching the viability of deleting the heat exchanger from the system on my 2001 Modena. I understand it’s not actually a cooler but it’s job is to get the transmission to operating temperature and keep it there. I actually did look for upgraded heat exchangers and looked for a couple that were recommended in older threads, one company doesn’t make them anymore and the other company doesn’t seem to exist. I would actually feel much more confident removing the potential for fluid cross contamination by using an air over oil cooler running a thermostat. I have previously set this up on a race/road car and had no problems with it running outside optimum temps. I really like the idea of setting up a cooler and never having that little worry about the integrity of the heat exchangers insides falling apart.
I do have a couple of questions
1. Is there a perfect temperature for the transmission because there are options regarding the thermostat temp you can purchase.
2. Does the trans use an oil pump for circulation?
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The big question: Why?

Are you using a non-yellow metal safe transaxle oil? No? Then your heat exchanger is safe.

If you're paranoid about the heat exchanger rotting out on you, then just buy a stock model and have it chemically nickel plated on the oil side. That will solve the problem and keep your car OEM.

 

Replacing a heat exchanger isn't a big job. Cleaning up the mess once one fails is a big job.

Just consider it a maintenance item, replace it every few years, and drive the car like you stole it. No muss, no fuss lol.

 

Question 1. I would assume the perfect temperature for the trans-cooler thermostat is around 180-190 F because that's what the coolant in the stock heat exchanger will be the majority of the time. That is the temperature that Ferrari is trying to keep the transmission at.

I'm also planning to do this same job, and will probably err a bit on the side of hotter as I'd rather have the gear oil a little too hot rather than too cold. Keep in mind most manual transmissions out there do NOT have coolers at all.

Q2. I assume it does, otherwise there would be no flow through the exchanger, but thats an assumption.

 

I haven’t heard of this nickel plating process. Is it common.

 

The heat exchanger doesn't suddenly explode. You can see oil in the coolant early. Change fluids regularly and you'll see it. Change it then and don't wait. One dude kept driving his when my mechanic told him not to because of leakage... killed the transmission. Do it early and you'll be OK. Enjoy the car...

 

If you have the time I don't think it'd take much to put a makeshift temp sensor inline with the trans oil hoses to establish a baseline, then bypass the heat exchanger by joining the hoses and check the new temperature. Decide from there whether to reattach the hoses or modify.

 

Another thing that be done is pull a vacuum on the cooling system. If it holds for five minutes without dropping, the heat exchanger is most likely fine.

 

I don't understand why everyone is trying to bypass the heat exchanger all of a sudden as opposed to doing basic maintenance and monitoring fluids.

 

What they don't get is it was done on the challenge cars for a reason. Those cars run with higher viscosity oils at higher temps for longer periods than the street cars do. The CS uses a water intercooler as well. I suspect that the colder transmission oil temps at startup in converted cars is going to kill syncros faster, esp for second gear.

 

If you have some mechanical sympathy, I don't see appreciable extra wear from shifting when the gearbox is not yet up to temp.

And most cars on the road don't have a gearbox fluid warming system and the synchros work well with good service life. They work in all sorts of climactic conditions.

The only argument I see for keeping the heat exchanger is that the 360 gearbox has twice the fluid capacity of a normal car's manual transmission and is larger physically also, with correspondingly larger thermal capacity. In that respect it will take longer to warm up to operating temp than a normal car.

However the cats and muffler are enclosing it which will speed up the process.

I just dont see any overwhelming necessity to keep the exchanger if you want to avoid the possibility of total gearbox failure.

Because a failure is silent and catastrophic and will cost you $20,000.

Also, even if you're lucky enough to catch the failure early, you will still have some degradation of the gearbox fluid from coolant contamination which will start damaging gearbox internals immediately.


Obviously you should do whatever makes you happy on own car
For me, deleting it will give me peace of mind.

 

A heat exchanger failure has so many obvious symptoms that an owner should discover the failure quickly.

Here's the test. Before you drive your car, check the coolant level. If it's low, that's a warning that something is wrong. Fill it back up and look for an oil sheen. If you see oil, that's bad.

Get one of those inexpensive vacuum coolant systems and pull a vacuum once a year. If it holds for five minutes without dropping, then your coolant system is intact and your heat exchanger isn't leaking.

It should never get to the point that you only wonder if something is wrong when the car can't shift anymore. That's an owner failure, not the car. Be sure to talk with your tech on the next major service about transaxle oil. If it is yellow metal safe, then your heat exchanger, and synchros, are going to be fine. If you don't know, change your transaxle oil now to one you know is yellow metal safe.

 

Few people outside of this Forum actually know what that means.
It also came out of several discussions over a few years involving some of the gurus here (Rifledriver, Taz, Flash etc), so not a wildly known fact.

 

I've worked on and built many high performance vehicles. No matter how you look at it the oem heat exchanger is a weak link. Routinely replacing the heat exchanger for piece of mind is still about a $2000 aud job and a destroyed transmission is about $30k aud. So you put in another heat exchanger and you're safe but you don't truly know how long for, you could end up with a brand new unit that fails prematurely and you have contaminated oil. The big scary problem here is the cross contamination of fluids that absolutely do not belong where they have often ended up and potential for killing the transmission. In a closed lubrication system with no filtration and definitely zero coalescing ability water in your oil is a devastating outcome. Why even have that worry in the back of your mind when I can set up a quality cooler with thermostat and hoses for less than half the exchanger cost and the worry is gone forever. The argument about keeping everything standard doesn't ring true if original is far inferior.

 

I think your evaluation of the heat exchanger is one based on mystery and mysticism, rather than logic and chemistry. The heat exchanger is made from copper. Copper is a yellow metal. If the oil in your transaxle isn't yellow metal safe, then yes, your heat exchanger and your very valuable syncros, are at risk.

So if you bypass the heat exchanger and still run an oil that isn't yellow metal safe, then your synchros are doomed. That's likely why the transaxle fails along with the heat exchanger, not because of the heat exchanger failure.

A bit of logic and chemistry go a long way towards understanding why the heat exchanger fails and what to do to prevent it.

 

I 100% agree with this.

 

How much pressure is going through the line in and out of the heat exchanger? Also,what size are the lines? Thanks

 

Does anyone here know why heat exchangers fail?

I have never seen a failed heat exchanger with any evidence of being chemically attacked.

You guys make it sound like it scientifically settled.

Why were the same parts used on 355s for many years prior and nearly no failures?

 

If you've never seen a heat exchanger fail with signs of being chemically attacked, then why did it fail?

I've seen two failed heat exchangers. Both showed the same failure: corrosion on the oil side.

 

There's a thread where a failed one was dissected and showed evidence of erosion of the tubes and black sludge stuck to the tubes. It appeared consistent with the way sulfur would attack copper/copper alloys. Maybe leading theory is a better term for it than scientifically settled.

It is odd that it's not a common problem on the 355. My speculation is that the 360 part might be of a slightly different material composition, the inner tubes are thinner, or higher temps or a stray electric current are accelerating the reaction.

 

Many cases of sludge from oil but we see that regularly no matter the oil used. Thats a sign of the oil being overheated. Never once a case metal being attacked once cleaned and examined.

360 has such a small ring and pinion no cooler will be the death of them. They are already regularly overheated. Ferrari put a cooler in them for very good reason. People really need to get over the idea its to heat up the oil. Are air/water intercoolers designed to heat intake air?
How come its never seen in 355 with same oils? Same part.

 

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The corroded tube at the bottom is taken from a failed heat exchanger from a 360. The tube at the top is how it should appear. About 90% of the copper is gone from the corroded tube.

What would you say is the reason why this heat exchanger failed?

 

The 360 maintenance schedule does not have coolant change intervals. I don't believe the 355 did, but you were forced to change most of the coolant with the engine out service. While that was my initial thoughts for the failure, Eastmemphis's dissection of the failed heat exchanger definitely questions that narrative.

 

The speed of chemical reactions depends exponentially on the temperature.

So if the failure mode is indeed corrosion and the (peak) oil temperatures are higher in the 360 than in the 355, it would be logical that the issue is much more prevalent on the 360.

In any case, the heat exchanger is there for a reason ... using yellow metal friendly oil can't hurt either.

 

Everyone in the FCA seems to know it’s from the oil side whereas on Fchat there seems to be a debate whether it’s the oil side or coolant side.

I am wondering if it’s an abrasion wear issue from the oil side! I’ll try and update more soon.