Overheating - time for a rebuild?

[Laitch]

I am looking into the procedure to change the buckets on the bike.  Clymers says I need two special BMW tools to get the camshafts out . . .

What the Clymer manual actually indicates is that you need those tools if you want to remove the camshafts without removing the timing chain cover and the timing chain. The tools were developed for production purposes. As Gryph mentions, it is perfectly possible to do the task without the tools; it's just more involved.

[Filmcamera]

A quick update


I found a new coolant








it says to use it instead of water so I will not dilute it, there is no need for anti freeze here so it will be 100% the new coolant.


I checked the thermostat and it does open correctly,  it is not a snap open but more of gradual opening starting at 85 C and ending by 90 C.  If left to cool it closes again.  I tested it various times and it opened and closed every time.


I took off the radiator to check the cooling fins better








There is some dirt in there and a pretty good ding in one corner but all in all I would say it is not too bad.


I did notice a rust like deposit on the  inside which is probably a mix of limescale and corrosion, hopefully a flushing agent will get rid of it.  The coolant that came out was almost totally clean though, very few extra particles in it at all.



Tomorrow I going to check the valve clearances again but attached is a chart showing what they were when I last checked them about 2500 miles ago.

[Martin]

The coating that is in the radiator will also be in the block and will be reducing the ability of the cooling system. You will see what happens after you use a good flushing agent, the water will not be running clean when you first drop the mixture. You need to clean and straighten any bent fins on the radiator. This is a tedious and time consuming activity which gives you the opportunity to connect with you inner being. Sanded and shaped popsicle sticks are ideal, be patient and gentle. Soak the radiator overnight in either water and detergent or vinegar to loosen the crap. Then use a hose to gently wash out the crap. Never use high pressure you can also use compressed air but you need to turn the pressure right down.
Regards Martin.

[johnny]

greetings...

if you are gonna f with that rudson snake oil you may wanna getts the yellow bottle...

all my bricks run hot... if you aint blowing the cap you are gòod to go...


coolant_green_container1.png (434.06 kB . 388x354 - viewed 435 times)

j o

[The Mighty Gryphon]

All in all, the fins don't look bent.  I would not screw with them.  Soak the fins in detergent or vinegar and gently flush them from the BACK side.  You might have to do it a couple of times to be absolutely sure all the crap is out of there.  When I did mine I flushed by pouring hot water from a gallon jug held about a foot above the fins.

That red coating in the radiator is something I've never seen in a cooling system.  I have a well and from time to time we are confronted with iron bacteria that turns everything a rusty red like what you have.  I suspect that someone before you might have been running well water in your bike.  Normally vinegar gets that crap out, but those rust stains can be pretty tough.  You probably need to get something stronger. 

[Laitch]

I have a well and from time to time we are confronted with iron bacteria that turns everything a rusty red like what you have.  I suspect that someone before you might have been running well water in your bike.

+1

[johnny]

greetings...

iron has good thermal conductivity...

j o

[daveson]

are there any vacuum leaks, that can cause overheating
or a compression test, eg head gasket leaking between adjacent cylinders
overheating only sometimes could be caused by either of those causes
in vacuum case by movement or lower revs than usual
leaking head gasket could be worse on shorter trips before the engine has heated or worse on longer trips, depending on where the leak is.

[rbm]

... I had a car with a standard temperature gauge that read high. I fitted an auxillary temperature gauge and it read low.

"A man with one watch knows the time; a man with two is never sure."

[Scott_]

Looking at that valve chart, all i can say is wowza.....If I read it correctly you have 10 of 16 that are too tight, granted not by much, but still outside of the tolerance range, 4 that are at the bare minimum and 2 that are fine.

#3 intake and #4 exhaust both a&b are right at the bare minimum.
#3 exhaust, both are just right.
All the rest are out of spec on the tight side.

BMW says not to(they want to sell you new ones), some riders here will also say not to, yet some riders have, and I have, "re-used buckets" or "moved buckets around" as needed to meet specs, with no ill effects.....
In my case I was able to move a bucket from a valve that was too loose and use it on a valve that had been too tight. It all depends on the thickness of your buckets and where they are at if you can re-use them or not.

The only way you are going to know what you need for new buckets is to pull the cams and inventory exactly what buckets you have and do the math. It may be possible to read the bucket spec, or you may have to measure it with a micrometer.

Re the radiator/engine cooling system, like others have mentioned, do a chemical flush to get as much of that scale out as possible as it does/will inhibit heat transfer, both in the block as well as in the radiator.
We have similar issue where I work, with our industrial chiller air conditioning system. Steel pipes and tap water cause a rusty scale inside the copper tubes of the chiller bundle. Even with continuous chemical treatment we still have to brush out the tubes every year to minimize/reduce/remove the coating inside the tubes that inhibits the heat transfer.

[Filmcamera]

Exactly, 10 of 16 too tight - and the great Chris Harris said in his 2v video if you are doing this on a 16v boke you are wasting your time, they never go tight...


That is partly why I plan to redo the measurements today.


 Meanwhile I have been working on the outside of the radiator, having soaked it overnight.  I swear it has not been this clean since it rolled of a West German production line in July 1990!

[Scott_]

FC, do note that the smallest bucket is a 2.50..... if you have a tight valve and the bucket is already a 2.50 you are NOT going to be happy as you will be looking at a head off valve job to replace the valve and seat...

[Filmcamera]

I just rechecked all the valve clearances and though there is some good news overall the picture is pretty much the same.


Number one cylinder intakes are the worst, 0.10 mm was a go but 0.13 mm was a no go, 0.15 mm is minimum so way tight


2 and 4 were also slightly tight 0.15 mm was a go but 0.18 mm was a no go so on the very limit and 3 was in the middle 0.18 mm go .20 mm no go


The exhaust side was better all four cylinders are in spec but 1 and 2 are at at the min, 0.25 mm was a go but 0.28mm was a no go.  3 and 4 were 0.28 mm go 0.30 mm no go.


So not one loose valve in the whole 16.  Obviously number one intake is the main concern.


Before I can take the valves out to see what buckets I need to buy I have to buy a valve spring compression tool (at least I think I do). Does anyone have a specific make or model they have used and liked on a K bike?

[Laitch]

Before I can take the valves out to see what buckets I need to buy I have to buy a valve spring compression tool (at least I think I do).

Where in the instructions did you get that idea?

[The Mighty Gryphon]

The only tool I needed to remove the buckets on Moby Brick was a magnet.

[Filmcamera]

In Clymers in the section about how to remove a valve but now you mention it I read the part again and it seems you can take the lifters out without removing the whole valve or cylinder head etc. 


So all I have to do is take off the valve cover and timing chain cover, remove the timing chain, remove the crankshafts and then I can pull out the lifters using a magnetic tool?


Then I just need to measure them, do some math, order new ones and wait for them to arrive. Then reverse the whole process. Is that more or less correct?

[The Mighty Gryphon]

I think you meant camshafts, but yes, that is about what is required.

[Filmcamera]

Oops, yes I did.  OK thanks, that is slightly less daunting than I had thought. 


I am going to wait a bit though, I want to try and ride during at least part of the season and also this is an expensive time of year to be doing fairly major repairs. Either way if the valve clearances have not changed in over a year a month or two more will be probably be ok.... famous last words I know.

[Scott_]

I'll add a little tip, before you remove the lower/exhaust camshaft, have your clean spots ready for the buckets as some may literally "fall" out from gravity(being at an upward angle in the head). The oil viscosity may provide enough resistance to keep them in place long enough to use a magnet on them, but I have had some not stay put.... just FYI.

The intake ones will stay put as they will be at a downward angle and you will want a magnet to help remove them.

[Filmcamera]

This morning I added some radiator flush and ran the bike at idle for twenty minutes, once it had got up to normal temperature, as the product instructions indicate.  During that time I noticed the fan came on at the correct temp indicated on the temp gauge - ie just under half way between 3/4 and the red line.  It also went off again at the correct place, just a hair over half way.  I allowed it to do two cycles and it did the same both times. 


I think that shows the temp gauge is approximately accurate.


Now I have to let the engine cool down then drain the flushing agent and run through with water until it runs clear.  I did buy a second bottle of radiator flush in case it is needed.


Whilst the bike was idling I took the time to take a few digital temperatures using my laser temperature gauge.  I noticed that the number one cylinder exhaust pipe was quite a lot cooler than the others.  I took the readings about one inch from where the header connects to the engine.  Number one was 175C and all the others were between 210C and 220 C.

[K1300S]

when was the last time the TB's were balanced?

[Filmcamera]

About six months ago or so.  I have ordered a leak down tester so when it gets here in a couple of weeks I was planning to do a compression test as well as a leak down test, I can easily enough add a TB balance as well.


So looking again at the valve clearance results, all the exhaust valves are either in the middle of the range or at the low end, none are out of spec.  Can I get away with just doing the intake valves meaning I only have to remove one camshaft or should I replace the exhaust valves that are in range but at min? What am I aiming for? Mid range, or max acceptable without be considered loose?  I think Clymer uses midrange ie 0.18mm for intake and 0.28mm for exhaust but given that Chris Harris said loose is ok is it maybe better to go for 0.20mm and 0.30mm?

[The Mighty Gryphon]

Valve clearance doesn't normally increase over time.  What you are adjusting for when you do the valves is the wear on the seat in the cylinder head, which as it wears closes up the gap between the valve and the cam.  For this reason, I always adjust for the maximum clearance so I have the maximum safety margin.  The valves on the 16v engines are such a pain in the ass to do, if I found one that absolutely needed a new bucket I would adjust it to the maximum clearance.  Since the damn buckets are so friggin' expensive I would just do the ones that are at the absolute minimum. 

Since you have several that are close but still in spec, and you're looking at riding season, you might want to just do the valves that are definitely out of spec and make a point of checking and keeping a record of clearances going forward.

You mention letting the bike idle and seeing the fan and the temperature gauge work properly.  Did the fan lower the temperature enough to shut off?  Was this after you cleaned the fins?  If  so, it might indicate that you are making some progress on the overheating issue.

[Filmcamera]

Yes the fan did lower the temp enough to shut off - at least the first time I did the radiator flush when it was a mixture of racing coolant and radiator flush in there.  I have just done a second flush with just water and the flush - this time the temp went into the red and although the fan cooled it enough to come out of there it stayed just under the 3/4 mark at which point the fan shut off again, the temp started to climb rapidly again so I left he fan turned on manually and it kept the temp at the just under the 3/4 mark for the rest of the time needed for the fush to do its stuff.


Now I am just waiting for the engine to cool enough to drain the radiator and run the engine with flowing water for a bit before refilling with the new OAT coolant I purchased.


On the valves I think you are right, I will do cylinders 1 and 4 on the intake side now and monitor the situation.  That means just one camshaft needs to come meaning I could even take the old buckets out to work out what ones I need to order then but them back in again to keep riding until they get here. With Max BMW and the time of year and customs etc I anticipate a minimum of three weeks from ordering the buckets to having them here to ready to install.


When I do order them is there anything else I need to replace at the same time? Is it just the buckets or do people typically change the springs or collars etc at the same time?

[The Mighty Gryphon]

When I did them on Moby Brick I just changed the buckets.  When you put everything back together, use plenty of oil on all the working surfaces.  Don't be like me and use an assembly paste with molybdenum in it.  The moly got into the engine oil, made the sprag clutch slip and required that I do a flush to get it out.