Coolant Reservoir Fix - with pictures

[N_igma]

Basically, I did a few things to my bike this week and I took some pictures, so I figured I'd post up to offer help to anyone needing it.

This is all on my 1999 748

First, I had the coolant reservoir crack. Imagine that. As per 2 different suggestions from 2 different well respected people, I came up with a method that I think should help the problem considerably. Here it is:

Needed:
Epoxy or silicone

Box knife or good scissors
Bicycle Intertubing - we don't need much

1) Remove tank
2) Remove airbox
3) Remove allen bolts holding on ignition stem. Set this aside
4) Unplug hose from coolant reservoir to radiator. Drain any coolant in there out
5) Unseat the atmospheric pressure sensor (right hand side of the reservoir) You just lift it up, but be gentle with it
6) Get your coolant reservoir tank out, drain it, and clean it off.
7) Take the rubber stopper sitting on top of the tank, out


Shave about 1/8" off the bottom of it. This rubber piece sits up slightly too high, causing extra pressure on your tank from the ignition stem.

8) Take your intertubing and cut yourself a piece a little shim. You'll want 3 or 4 identical pieces like this. See the picture for sizing


Silicone/epoxy these pieces together to make one piece that's 3 or 4 thick. This will provide a slightly cushioned barrier for where the airbox and tank are being forced forward, putting pressure on the front of the reservoir.

9) Silicone/epoxy the shim you've created to the front of the tank like shown in the pictures.


Let this dry completely, put the little rubber stopper thing back in the top of the reservoir. Reinstall

This has worked fine for me so far, and I've been assured from experts that it should work also. So we'll see. Hopefully this is helpful

I'll be posting another thread in a minute on replacing your airbox gasket (the one that seals against the gas tank), and using an inbox air filter. Will be titled "Airbox Gasket Replace/Aftermarket Air Filter" for later searching

[Flip998FE]

Cool, thanks for the write-up. I'm gona try that while my bike is apart.

[94CobraR]

Looks like a Hall of Wisdom posting to me.

[N_igma]

If someone deems it worthy, I'd be thrilled to have it in there

[tye1138]

Good job on the write-up and pix! Its a kool idea to help prevent expansion, but the rubber and epoxy will do the opposite, it will constrict the plastic in the area used. We are trying to get away from constricting the tank in any area by cutting down the rubber grommet that holds it in place.

Your on the right track though, keeping things from hitting the bottle is great. Sure the bottle can twist and move around on its own, but the fuel tank/airbox putting forces on the coolant tank? Next time I'm at the track, I'll stick a piece of foam there and see if it gets compressed.

[N_igma]

Originally Posted by tye1138

Good job on the write-up and pix! Its a kool idea to help prevent expansion, but the rubber and epoxy will do the opposite, it will constrict the plastic in the area used. We are trying to get away from constricting the tank in any area by cutting down the rubber grommet that holds it in place.

Your on the right track though, keeping things from hitting the bottle is great. Sure the bottle can twist and move around on its own, but the fuel tank/airbox putting forces on the coolant tank? Next time I'm at the track, I'll stick a piece of foam there and see if it gets compressed.

You should do that, because I understand your disbelief, but the man that told me about that is a registered Ducati mechanic (for about 20 years), and travels to Italy constantly for training. So I was just kinda taking what he said as gospel

[level7]

I've looked high and low for a compatible epoxy/cement/glue. All options at Lowes/Home Depot came up short. I believe that that epoxy may have a temperature limitation and/or a pressure limitation and/or plastic compatibility issue? Check the back and let us know. It could be a new product that I haven't seen yet.

One more thing, he didn't tell you to drill out the ends of the cracks to prevent further cracking?

That was my approach, I would drill out the ends of the crack so the crack couldn't go any further then plug the holes and crack with epoxy. But I haven't found the right epoxy yet.

[n8nod9it]

A silicone adhesive will work best between dissimilar surfaces such as the PE coolant bottle and the rubber innertube. Don't use Epoxy as it doesnt have the correct elasticity for the hot coolant bottle to cooler rubber patch.

[tye1138]

I did a test last night and took some measurements. With either the DP carbon fiber airbox OR standard airbox, the gap between the fuel tank/airbox to the coolant is more then 16mm. Pushing the coolant bottle towards the airbox, it didn't even hit because the rubber nubby on the top, prevented it.

Not to place errant blame on anybody, but did your tech talk about cleaning your pressure relief valve out on a regular basis and using the proper coolant? I know many people who still race older superbikes who've never had a blown coolant tank on a 916/748 series bike (998's are different). I also know a whole host of people who've had blown tanks on the street. The key isn't to glue things onto the tank, its to monitor pressure or an easier method is to monitor temperature. The higher the temp, the greater the pressure. I don't have a fan on my bike on the track because you don't need one and my temps never raise above 180. If your repeatedly running around or over 210, thats going to eventually cause damage. The key number here is 180... keeping it right around there, will help substantially.

The first thing is to buy the motowheels temp sensor that kicks the fan on earlier and also buy there aluminum fan blades to help move more air.
The second step is to use a coolant that helps keep the boiling point down, like water wetter.
The third step is to keep your pressure relief valve cleaned at all times and test it if possible.
The fourth step is to keep the tank clear of any obstacles so its almost free-floating in its compartment.
The fifth step is to make sure the over-flow tank (under the airbox) isn't full, or over flowing. Once your coolant level is set, that tank should be emptied.

I almost guarantee you, if you bought a new tank and did those 5 steps, you'll probably never have another burst again.

Originally Posted by n8nod9it

A silicone adhesive will work best between dissimilar surfaces such as the PE coolant bottle and the rubber innertube. Don't use Epoxy as it doesnt have the correct elasticity for the hot coolant bottle to cooler rubber patch.

I thought so...

[n8nod9it]

Originally Posted by tye1138

I did a test last night and took some measurements. With either the DP carbon fiber airbox OR standard airbox, the gap between the fuel tank/airbox to the coolant is more then 16mm. Pushing the coolant bottle towards the airbox, it didn't even hit because the rubber nubby on the top, prevented it.

Not to place errant blame on anybody, but did your tech talk about cleaning your pressure relief valve out on a regular basis and using the proper coolant? I know many people who still race older superbikes who've never had a blown coolant tank on a 916/748 series bike (998's are different). I also know a whole host of people who've had blown tanks on the street. The key isn't to glue things onto the tank, its to monitor pressure or an easier method is to monitor temperature. The higher the temp, the greater the pressure. I don't have a fan on my bike on the track because you don't need one and my temps never raise above 180. If your repeatedly running around or over 210, thats going to eventually cause damage. The key number here is 180... keeping it right around there, will help substantially.

The first thing is to buy the motowheels temp sensor that kicks the fan on earlier and also buy there aluminum fan blades to help move more air.
The second step is to use a coolant that helps keep the boiling point down, like water wetter.
The third step is to keep your pressure relief valve cleaned at all times and test it if possible.
The fourth step is to keep the tank clear of any obstacles so its almost free-floating in its compartment.
The fifth step is to make sure the over-flow tank (under the airbox) isn't full, or over flowing. Once your coolant level is set, that tank should be emptied.

I almost guarantee you, if you bought a new tank and did those 5 steps, you'll probably never have another burst again.



I thought so...

^^Sounds reasonable. I've never blown a tank on 13 years of service on my bike. Nothing hits the coolant tank...