Radiator oxidation

bmwk100rs · 1 Radiator oxidation Wed Jun 09, 2021 4:12 pm

bmwk100rs

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Number of posts : 111

Hi everyone,

I recently purchased a 1987 K100RS with only 53K miles on it. The bike starts and runs fine, and it has not leaked fluids on the garage floor since I rode and parked it two weeks ago. Today, I started to do a full inspection to replaces fluids and any necessary part (e.g. bearing, seals, clutch, etc.). However, the first thing I noticed it was the oxidation and water marks on the radiator. Is this normal on the K100s or could this be caused by a crack in the radiator or damaged hose or loose clamp. Any advice on how to check or test it will be appreciated. TIA!

Snod Blatter · 2 Re: Radiator oxidation Wed Jun 09, 2021 7:27 pm

Snod Blatter

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Number of posts : 488

Considering the radiator and engine are made of aluminium I find the brown rust quite strange. Are you sure it hasn't just been splashed through a really muddy puddle or something?

When mine leaked (twice now..) I just had a wet patch in the fins and blue antifreeze crystals underneath the radiator. Nothing like this.

moriarti · 3 Re: Radiator oxidation Wed Jun 09, 2021 7:46 pm

moriarti

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Number of posts : 700

No its not normal. Im thinking wrong antifreeze or caustic cleaner has been used. Remove rad. Flush and test including hoses.Sould you find a load of crap flush full system to be safe.

Dai · 4 Re: Radiator oxidation Thu Jun 10, 2021 5:10 am

Dai

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I think that's possibly been splashed on from somewhere else. Check the grill on the lower front fairing - if that's rusty then it could be your discolouration source. Riding through a rusty puddle could also have done it. Also if the coolant has been in there for a long time I have also seen the inside of two radiators turn rust-coloured and the coolant came out looking lke a sluice from the Mississippi. It's obviously not a leak because otherwise as Snod says, you'd see a leak point.

Laitch · 5 Re: Radiator oxidation Thu Jun 10, 2021 1:05 pm

Laitch

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That looks like arid-land deposits. Did you get it from around San Bernardino, from around Palm Springs or east of Escondido? Smile

Disconnect the battery ground cable from the transmission after you've ridden it when you intend to put it away for days or weeks at a time. When the battery voltage drops, the starter relay contacts could fuse and you'll wonder why the starter won't shut off. If you habitually connect the battery to a battery tender that might be sufficient, if the battery is still in good condition. A battery isolator switch is a useful addition.

bmwk100rs · 6 Re: Radiator oxidation Tue Jun 15, 2021 12:40 am

bmwk100rs

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Number of posts : 111

Thanks everyone for your comments and suggestions. Today, I removed the radiator and used a compressor to blow out from the backside dirt and bugs. After that, I sprayed both sides with a garden hose on low pressure to flushed off the exterior. It looks much better now (see pics below). However, it seems that it's time to replace hoses and clamps for the engine intake L connection. Or, should I just clean them up and tie the clamps. What do you think?

Dai · 7 Re: Radiator oxidation Tue Jun 15, 2021 7:23 am

Dai

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Cooling system hoses usually survive years of abuse. I would, however, pull them off the thermostat housing and clean the ally spigot. It almost certainly looks worse than it really is, but as you're that far in anyway...

That radiator looks in really good condition, BTW.

Point-Seven-five · 8 Re: Radiator oxidation Tue Jun 15, 2021 8:21 am

Point-Seven-five

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+1 on Dai's advice. My experience is that the only way these hoses fail is through a crash.

Judging from the photos, I suspect hard water was used in the cooling system. Remove the hoses and all the cruddy cooling parts and do a vinegar soak for a couple hours followed by a good rinse.

Put everything back together and then do a complete cooling system flush with distilled water and vinegar to clean out the passages. You might have to do it a couple times to clean things out completely. Based on the mineral deposits in the photos this is critical to have good cooling.

Last, keep your fingers crossed that the water pump is still good.

Laitch · 9 Re: Radiator oxidation Tue Jun 15, 2021 9:28 am

Laitch

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bmwk100rs wrote: should I just clean them up and tie the clamps. What do you think?

I'm involved in coffee titration right now so comprehension is still slow. What is meant by tie the clamps?

bmwk100rs · 10 Re: Radiator oxidation Tue Jun 15, 2021 5:00 pm

bmwk100rs

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Number of posts : 111

Laitch wrote:What is meant by tie the clamps?

Haha! I meant tighten the clamps!

Point-Seven-five + Dai wrote:Remove the hoses and do a vinegar soak for a couple hours followed by a good rinse. Then, do a complete cooling system flush with distilled water and vinegar to clean out the passages.

Good suggestion, will do exactly that.

I'm also planning to rebuild the oil+water pump.

Thank you, both!

bmwk100rs · 11 Re: Radiator oxidation Wed Jun 16, 2021 1:34 am

bmwk100rs

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Number of posts : 111

After I removed the hoses to to do the vinegar soak, I noticed a little tube without any hose attached to it. Is that normal? Is it some kind of breather pipe?

Dai · 12 Re: Radiator oxidation Wed Jun 16, 2021 4:33 am

Dai

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That's for you special people in Cali-for-ni-a Very Happy

. It's an emissions breather which I believe is specific to that state. Cap it off and ignore it.

bmwk100rs · 13 Re: Radiator oxidation Wed Jun 16, 2021 11:24 pm

bmwk100rs

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Number of posts : 111

Dai wrote:It's an emissions breather which I believe is specific to that state. Cap it off and ignore it.

Thanks Dai for confirming. Should it be connected to the hose that connects to the fuel tank?

Dai · 14 Re: Radiator oxidation Thu Jun 17, 2021 7:10 pm

Dai

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That depends on which fuel tank you have. Piccy of the underside?

bmwk100rs · 15 Re: Radiator oxidation Thu Jun 17, 2021 8:55 pm

bmwk100rs

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Number of posts : 111

Dai wrote:Piccy of the underside?

Laitch · 16 Re: Radiator oxidation Thu Jun 17, 2021 9:38 pm

Laitch

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Number of posts : 3251

The arrow points at the drain port that dumps water collected from around the cap opening. Next to it is the vapor release port that formerly was vented to the crankcase and had a pressure relief valve in the line as indicated by your diagram. You can attach a hose to that port and route it to dump behind the right foot peg plate; the water drain hose dumps there too. The alternative is to buy BMW's accumulator cup, hang it on the frame beneath the tank where the ports exit, then route one hose from the cup that dumps behind the right foot peg plate. The cup is inexpensive and makes a great stocking stuffer or party favor.

Dai · 17 Re: Radiator oxidation Fri Jun 18, 2021 7:59 pm

Dai

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Number of posts : 5700

As Laitch says: connect to the forward spigot, otherwise just cap it off and ignore it. If you decide to connect one to the other, you really, really, really don't need that one-way valve. While I have to agree with a lot of California's green/environmental ideas, sometimes I think they go a bit too far e.g. the 'known to the State of California to cause cancer' on just about everything.

Laitch · 18 Re: Radiator oxidation Fri Jun 18, 2021 8:27 pm

Laitch

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Number of posts : 3251

Dai wrote:As Laitch says: connect to the forward spigot . . .

Did I say that? Which forward spigot—the one on the tank or the one on the crankcase? The weather has been so good here it's hard for me to care right now but I believe I must. Sad

Regardless, bin the one-way valve then stopper up the port on the crankcase using a stub hose with a bolt in it or the hose simply folded and zip-tied. That emission system is a loser, as are many of California's nannyfied regulations. That tank port is meant as a vapor release to supplement the fuel cap's release. If you don't put a hose on it one way or the other as I described, you'll often be smelling fuel vapor if your olfactory system is processing at an optimal degree. Smile

Last edited by Laitch on Fri Jun 18, 2021 9:09 pm; edited 2 times in total

Point-Seven-five · 19 Re: Radiator oxidation Fri Jun 18, 2021 8:27 pm

Point-Seven-five

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Dai wrote:sometimes I think they go a bit too far e.g. the 'known to the State of California to cause cancer' on ~~just about~~ everything.

FIFY

brickrider2 · 20 Re: Radiator oxidation Mon Jul 05, 2021 2:06 am

brickrider2

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Number of posts : 729

What are the benefits/disadvantages of using vinegar to flush the cooling system - as opposed to a commercial product from an auto supply store? It is obvious that using vinegar would be most economical, but beyond that, is there any difference?

moriarti · 21 Re: Radiator oxidation Mon Jul 05, 2021 4:31 am

moriarti

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Number of posts : 700

Vinegar being a very mild acid is less likely to cause damage than a
Caustic based rad clean product, and in case of spillage wont damage paintwork, or engine surfaces. Thats my take on it.

Point-Seven-five · 22 Re: Radiator oxidation Mon Jul 05, 2021 7:44 am

Point-Seven-five

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Number of posts : 4216

Price... Plus, it will marinate the bugs caught in the fins and make them taste better and easier to flush out.

brickrider2 · 23 Re: Radiator oxidation Mon Jul 05, 2021 11:55 am

brickrider2

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Number of posts : 729

My plan is to use vinegar inside the radiator. I'll replace the coolant with vinegar, run the bike until it reaches operating temperature, then let is sit a day or two. Cleaning the remains of insects from the exterior is best done with hydrogen peroxide.
I probably will change the oil as well. My ride back from the BMW Owners Rally was sizzling and the bike's temp gauge sat on the edge of the red zone for a long, long time. Rolling Eyes

Point-Seven-five · 24 Re: Radiator oxidation Mon Jul 05, 2021 12:21 pm

Point-Seven-five

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Number of posts : 4216

Flush the cooling system, then remove the radiator and do a good soak both internal and external. I had a an overheating problem on a 16valve K100RS that was caused by minerals in the radiator and enough insects to feed a family of four jammed in the fins.

See if you can find a radiator fin "comb" to straighten any collapsed fins. In hot weather you need every bit of airflow you can through the radiator. Then make a 60% water coolant mix for the engine. With all that done, you should be able to run continuously in temperatures above 100F and never go above half way on the temperature gauge.

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1 Radiator oxidation Wed Jun 09, 2021 4:12 pm

bmwk100rs

2 Re: Radiator oxidation Wed Jun 09, 2021 7:27 pm

Snod Blatter

3 Re: Radiator oxidation Wed Jun 09, 2021 7:46 pm

moriarti

4 Re: Radiator oxidation Thu Jun 10, 2021 5:10 am

Dai

5 Re: Radiator oxidation Thu Jun 10, 2021 1:05 pm

Laitch

6 Re: Radiator oxidation Tue Jun 15, 2021 12:40 am

bmwk100rs

7 Re: Radiator oxidation Tue Jun 15, 2021 7:23 am

Dai

8 Re: Radiator oxidation Tue Jun 15, 2021 8:21 am

Point-Seven-five

9 Re: Radiator oxidation Tue Jun 15, 2021 9:28 am

Laitch

10 Re: Radiator oxidation Tue Jun 15, 2021 5:00 pm

bmwk100rs

11 Re: Radiator oxidation Wed Jun 16, 2021 1:34 am

bmwk100rs

12 Re: Radiator oxidation Wed Jun 16, 2021 4:33 am

Dai

13 Re: Radiator oxidation Wed Jun 16, 2021 11:24 pm

bmwk100rs

14 Re: Radiator oxidation Thu Jun 17, 2021 7:10 pm

Dai

15 Re: Radiator oxidation Thu Jun 17, 2021 8:55 pm

bmwk100rs

16 Re: Radiator oxidation Thu Jun 17, 2021 9:38 pm

Laitch

17 Re: Radiator oxidation Fri Jun 18, 2021 7:59 pm

Dai

18 Re: Radiator oxidation Fri Jun 18, 2021 8:27 pm

Laitch

19 Re: Radiator oxidation Fri Jun 18, 2021 8:27 pm

Point-Seven-five

20 Re: Radiator oxidation Mon Jul 05, 2021 2:06 am

brickrider2

21 Re: Radiator oxidation Mon Jul 05, 2021 4:31 am

moriarti

22 Re: Radiator oxidation Mon Jul 05, 2021 7:44 am

Point-Seven-five

23 Re: Radiator oxidation Mon Jul 05, 2021 11:55 am

brickrider2

24 Re: Radiator oxidation Mon Jul 05, 2021 12:21 pm

Point-Seven-five

25 Re: Radiator oxidation

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