Coolant leak at rear

Just fixed mine and had to pull the intake manifold. Had the same signs as you, didn't notice anything until I was under the car and saw remnants of coolant on the exhaust.
Stupid design by Ferrari.

 

How do you feel about 50% of the worlds cars that require pulling the dash to replace a heater hose or heater core?

I have been in the business for nearly 45 years and there is nothing stupid about that design. It is vastly easier to work on than a great many far more common and mundane cars. Engineering anything is a matter of trade offs and Ferrari did an outstanding job on that one.

My Ford F150 recently required removing most of the top of the engine to replace a bad vacuum hose fitting so I could get the check engine light out to get it smogged.

Early Bentley GTs required engine removal to replace headlights and most required removal to replace their vacuum hoses en mass due to age and leakage.

I could go one for days. I wish all cars were as well thought out as the 550.

If you want easy to fix a Trabant is probably a better choice.

 

Coolant stains on the bottom of the bell housing or cats is typically from the hoses under the manifold.

The car is around 20 or so years old. Hose replacements at this point in life are no big surprise.

 

Yep, plenty of other manufacturers have poor designs as well.

Ferrari could have easily made hard lines under the intake manifold and the connection for the small soft hose connection at the rear of the intake manifold. Also, considering how the hose failure has been a long-time and common issue on 456, 550 & 575 . . . I stand by 'stupid design' comment. At least the later cars have the reinforced hoses so they last longer.

 

Ouch, that's a tough one

 

The 575 updated the three big hoses to silicone, which lasts much longer, but the smaller hoses are still 1950s rubber and those tend to clog, wear, and leak. Especially if she has not had regular changes of coolant.

 

Plenum removal/re-installation is much easier if you use a magnetic screw bit

 

I'm 87 with a bum left shoulder and I had mine off and on the bench in 45 minutes start to finish. Just get the proper tools lined up before you start. There are lots of "How to' posts here. You will need help lifting the plenum off.

 

Venting?

So there is no misunderstanding. At a dealer with repair order in hand and a fully assembled car out there in the lot somewhere, bringing it it, putting it on the hoist, removing the belly pan, draining the coolant, removing the manifold, cleaning the top of the motor, getting the parts from the parts department, replacing the hoses and gaskets, reassembling everything, test driving the car, cleaning your tools and work area is going to be a good deal more than twice the time Dave quoted to take his manifold off.

 

When I said 45 minutes that did not include all the things Brian talked about as all I needed to do was replace the plenum gasket. I was surprised myself at how little time it took to get the manifold/plenum off and on the bench.

When I did the hoses last year I took my time and that was a longer job by quite a bit.

While you're there you should replace all gaskets including plenum and replace the linkage black plastic rod ends with all metal ends same as on the throttle cable.

I would replace both temperature sensors as well.

If using the Dave Helms hose kit do not use the supplied hose clamps, rather use an overlapping type, Aba is a good brand and position the screws so they can be accessed with the manifold on for later tightening.

Another tip is not to re-use the manifold nuts as they are Nyloc and the engine heat will cause them to loose their holding ability, rather use an all metal locking nut.
NTL6YLW - Conical Lock Flange Nut Yellow Zinc [NTL6YLW] - $0.27 : Bel-Metric, Metric Hardware, Metric Fasteners, Metric Bolts, Metric Nuts & Time-Sert Thread Repair

 

Looks like Bel-Metric has discontinued these nuts but Amazon has a similar nut
25 M6-1.0 Exhaust Lock Nuts Copper Plated Steel 9mm Hex: Other Automotive Parts: Amazon.com: Industrial & Scientific

 

Belay the above, this is what you want
NTLH6YLW - Conical Lock Flange Nut Yellow Zinc CL10 [NTLH6YLW] - $0.27 : Bel-Metric, Metric Hardware, Metric Fasteners, Metric Bolts, Metric Nuts & Time-Sert Thread Repair (belmetric.com)

On the package I have here it says they are made in Germany, a search might find then

 

I really hate prevailing torque fasteners but in this case I agree with Dave and use PT nuts.

The bel metric page is here
https://www.belmetric.com/coarse-c-3_54_950/?zenid=kqnetrq8s5i1comc5feboefek4

I'm not sure those copper exhaust nuts are PT. They might be just copper to prevent corrosion seizure that often happens when you use steel nuts on steel threaded header studs.

A PT nut is sort of bend at the top to add extra friction and prevent the initial lost of torque and the PT part also keeps friction of it the nut is loose it does not back out.

This plenum job is just tedious and need attention to detail. You don't want nut or washer to end up inside the intake. So look and be careful. Look to see if there is just a nut or nut and washer. These cars are decades old and many hands have been in there before you. Just because the first 6 there is no washer under the nut does not mean the 7th has no washer. When you pull the plenum off those thinks have a way of landing in a bad spot. Use magnets here. If you don't have a 10mm magnetic socket don't even start the job. I'm also a big fan of my long reach needle nose pliers to get stuff.

This is a good time to not only get the hoses under but the ones on the back pipes that run near firewall. Those are often ignored.

 

Bovien, a couple years ago I removed my manifold to replace the coolant sensors. Did a write up here. The one thing I would add is to get an engine hoist. The manifold is not too bad, but it is awkward as you have to lean over to hoist it up. Here was the thread:

https://www.ferrarichat.com/forum/threads/removing-intake-manifold.605360/

 

Last winter I had my manifold off. As I have a bad back, I removed the side plenums/covers first, to reduce the weight.
I managed to get it off and later on again that way by my own, so it is certainly doable without an engine hoist. (but a hoist is a good idea!)
.
And as others have said, buy or make a 10mm magnetic swivel socket, and remove the nut and washers with an extra magnet on a stick next to it, so any washers that might be there will get caught before they end op in the intakes. And buy a glassfibre camera for 50 euro, so you can see well into the intakes for double checking.
When you have it all back on again, do not forget to check and maybe retorque the nuts after a few heatcycles.

Another tip for the fuel rails (if you have removed them), prepare the complete rail on the bench, lign the injectors up (refitting the clips on the injectors is easy at that time, but not when the rail is on the manifold)
Ligning them up before you refit prevents that some injectors are misaligned with the holes, making refitting difficult, as there is not much space to do that in situ.

 

Hi,

Learned that lesson checking the valve clearances for the first time on the V12 E-type, LH manifold came out fine, RH side kinked at the choke cable and a couple of washers ran into the inlet tract. Inlet valve nr 5 was open!

I got it out the next day with a borescope camera, a magnet and a coat hanger, but it wasn’t easy!

Magnets and carefulness are your friends.

Cheers!