ST1100 Cracked Block

rcmcy

Joined
Apr 18, 2016
Messages
5
Location
eagleby australia
I find every ST1100 I look at old or late model low or high mileage has a cracked block so with a laser temp machine I have taken some temps of the RH rear block by the drain screw which appears to be where the cracks start.
Temps of 140c and above have been registered on every bike I have tried all the other cylinders have temps of 100c or even less.
So it seems that the coolant is boiling in the rear and causing hot spots resulting in the cracking.
Looking into the right angle water connections under the carbs it looked like the rear cylinder had a smaller outlet than the rest but by enlarging the clearance in the head did not decrease the temp.
It appears there is virtually no coolant circulation in the RH rear block.
A Band aid fix is to use Waterless coolant such as Evans which they claim has a boiling point of 190c, as this is above the 140c plus measured it may stop the hot spots and help reduce or cure the cracking problem.
Anybody else got any ideas or has somebody got an old cracked block that can be cut open and have a look to see if it can be modified to increase or make the coolant flow in the problem area.
Cheers
Ron
 
Every one, Ron? Lots of high mileage STs have no signs of a crack. Only one of my three cracked. Admittedly, there have been many, but not all in my experience. Maybe Australia is just that much hotter? :D

My considered opinion, the lower case casting has to be nearly perfect or there will be a thin spot at that location. Add in the need to drill thru from the rear to join the cast passages (hence the freeze plug in that location) and the opportunity for failure are increased. Certainly a possibility a narrow passage could contribute to the problem. Are you finding physical evidence of coolant leak or are you confusing the casting flash marks. All the blocks show that anomaly even when no cracks are present.
 
I plan on keeping mine until it dies. And that may be after I die, if Alex Schmidt's ST1100 is a typical example.
 
I've never even heard of this 'problem' on an ST1100.
 
Jim Van said:
I plan on keeping mine until it dies. And that may be after I die, if Alex Schmidt's ST1100 is a typical example.
Click to expand...

Didn't you recently opt to increase the engine operating temperature with a higher rated thermostat? Maybe you should be concerned, if there is any substance to Ron's complaint?
 
Last edited:
I've never even heard of this 'problem' on an ST1100.
Click to expand...


There have been several reports over the years. They started casting the blocks in '89/'90. Doubt the process was ever changed. How good was the technology back then?

Many 1100 with mega miles. Last I heard Alex was retiring his at 400K miles.
 
Ron said:
They started casting the blocks in '89/'90. Doubt the process was ever changed. How good was the technology back then?
Click to expand...

how much has the technology of pouring molten aluminum into a mold changed in the last 25 years, anyone know? I'm guessing that technology hasn't changed much during that time, but I have no idea.
 
Hi
You guys are missing the point its not the casting the problem is no coolant circulation in the RH rear if you look at the 10mil coolant drain plug the cracks start usually down from the drain plug.
The problem looks to be the water pump is delivering more coolant to the left hand side, currently looking for an impeller which will circulate more coolant and maybe a mod so more flow is to the Right.
You state no cracks I currently have 3 ST,s in the workshop plus a wreck written off several years ago all are cracked but not leaking coolant yet.
 
paulcb said:
I've never even heard of this 'problem' on an ST1100.
Click to expand...
IIRC were there a few '94 engines with casting flaws on #3 (or #1? I do remember RH bank though...) scattered around the globe(!)...
That rare issue probably grew legs, wandered and now makes its return relabelled as "general design flaw" here... ;-)

And if we consider that there SC26 plants with 400,000 or 500,000 kilometres around without having blown up yet... :cool:
 
I suspect these are typical casting flaws that can mimic a crack. There have been a couple of reported cracked blocks but I would hardly call in an epidemic. I do use Evans waterless coolant in all my vehicles and have done so for years. It is hard to convince people of its advantages as some people are convinced that it does not cool as well as conventional water based coolants. I have had very good success with it. it will continue to work in very critical temperature situations where water based coolant absolutely break down. No corrosion what so ever being there is no water.


Dan
 
Hi
I suggest you Google ST1100 cracked block where you will find more details than I can supply plus lots of pictures of cracks, I am hoping by using waterless coolant (Evans is one brand)which boils at a higher temperature it will stop the cracks getting worse and leaking coolant.
Just a theory at this stage, I would like to try and modify the water pump impeller to direct more flow to the right hand side but that's a job in the future when I can scrounge some old pumps off small cars and find an impeller to modify.
I found out about the serious of this problem when a Gold Coast dealer wanted to buy a second hand motor from me because he had an ST badly cracked and leaking coolant, on checking my 3 ST's and the wreck he wanted to buy they were all cracked but not leaking coolant yet.
If you shine a good light up through the oil inspection hole so it shines upwards behind the exhaust pipe RH Rear and find the 10mil coolant drain plug the cracks seem to start from this plug usually downwards but look on the net lots of photo's there
Cheers
Ron
 
rcmcy said:
Hi
I suggest you Google ST1100 cracked block where you will find more details than I can supply plus lots of pictures of cracks
Ron
Click to expand...

I did as you suggested and found only 1 example of a cracked block on an ST1100 that had been in a Major accident.
 
Last edited:
rcmcy said:
Hi
I would like to try and modify the water pump impeller to direct more flow to the right hand side but that's a job in the future Ron
Click to expand...

Somebody posted a thread and pictures of his modified water pump recently (on this site). I'm sorry, I did not note down any particulars but I think he used an impeller from a car and pressed it onto the ST's shaft. Again, my memory of this is hazy (1100 or 1300?) because I found it of academic interest - not something I am about to do. This new impeller certainly looked like it would pump more water than the orginal - if you can find the thread it might prove to be a big help to you.

Can anyone else give Ron a link to this thread?
 
You must log in or register to reply here.
Back
Top Bottom