Help - Cooling system compromise KTM 300 XC-W

[blakeNY9 0]

Reaching out for some 300 2T expertise.

I have a comprise between the cooling system and the engine on my 08 300 XCW. The cooling system is getting pressurized by what has to be exhaust gas. I'm running Evans waterless coolant, so it isn't boiling and pressurizing that way. I'm pushing a 1/4 to 1/2 cup of coolant into the overflow recovery tank every ride and seems to be getting worse. I have a KTM cooling fan kit installed as well and the bikes overflowing even without the fan coming on (yes the fan is operational and functioning properly) i.e. bikes overflowing without being hot (yes coolant is filled to proper level just above the fins, and is then below the fins after every ride) Also, last ride was told by guy behind me that he could smell some coolant in my exhaust, but only at start up.

Some history... Took it to C&D back in Nov for this same problem and they found a striped bolt on the cylinder top which they surmised was letting exhaust gas leak by into cooling system. They fixed it at the time, so it could have happened again (need to check the bolts). Also I was leaking coolant at the exhaust flange where the cooling channels route thru, I replaced the 4 O-rings in that and it seems to have stopped. The bike has gotten pretty hot twice, at Tecate Enduro and one other time when the same plastic connector failed as at the enduro but I had to get back to the truck. It's possible I have fried some O-rings etc.

My question not being terrible familiar with the internal workings and passages... where are all the places this compromise could be happening? I want to replace all the seals/O-rings in the spots that this leak by could be happening. From looking at parts diagrams I think the two below O-rings on the top of the cylinder is one place.... where else?

Cylinder, Cylinder Head diagram

21. O-Ring 78,00X2,00 Vit. Black 0770078020

22. O-Ring 105,00X2,00 07 0770105020

[amgems 79]

Hey Blake, Have you posted / searched on KTM Talk?
If no "experts" here can help, they have a lot of "experts" over there too.

Crack in the cylinder, or head?

Pressure check might help ?

I wish I could help, but my last 2 stroke was air cooled.

[mtnmanseth 0]

Failed or failing base gasket! Easy fix. Call me.

Edit: Actually, can I change my answer, Trebek? How did C&D repair a stripped head bolt? Helicoil? I'd look at that first for sure. If that one bolt isn't holding perfect, like the others, it can probably pass a little air in and coolant out, which would lead to a lean condition and coolant in your exhaust. Also, a failed or failing o-ring could do this. Also, a failed or failing base gasket could be contributing. I would be suspect of a repaired/helicoiled cylinder bolt hole for sure, but C&D knows way better than me. You may want to price a new cylinder and new piston kit, unfortunately. Start by changing the two o-rings and torquing all head bolts in a star pattern is step one, though. Spaugh should chime in here too...

[tntmo 901]

I was thinking along the same line as Seth. I'd replace the base gasket, the O-rings and carefully check the torque on all the bolts to see if they feel like they are stripping out since you've already had one issue.

[blakeNY9 0]

Thanks for the responses.

Yes, bolt repaired with Helicoil.

Parts sheet/diagram has 4 different base gaskets listed. Any idea which one I should order? Why are there different ones? Looks like different thicknesses....

http://oemparts.chaparral-racing.com/oemparts/a/ktm/524b8ceff8700231ac498b93/cylinder-cylinder-head

Gasket Cylinder Base 0,2Mm 03

5483003000

Gasket Cylinder Base 0,4Mm 03

54830030004

Gasket Cylinder Base 0,5Mm 03

54830030005

Gasket Cylinder Base 0,75Mm 03

54830030075

[Bp619 104]

Thicker should be less power reducing compression ratio

[mtnmanseth 0]

You should run whatever base gasket or combination of base gaskets are in the bike today. Running a thinner base gasket can increase compression and bottom end torque by changing exhaust port timing, but without knowing your squish it could lead to a major problem. You won't know what's installed today without tearing it down and measuring, unfortunately.

[mtnmanseth 0]

Ps. Here is squish band test instructions from the machine shop that machined the head on my GasGas...

http://www.rb-designs.com/rb_designs_llc_017.htm

[tntmo 901]

If you read the KTM service manual, you set your "X dimension" with the different base gaskets.

Do a Google search to find out about it and how to set it, but if you can figure out what you were running before I'd just use the same one. I just did a complete crank/rod/piston on my 300 and that's what I did.

[robertaccio 412]

I have not looked in while but sometimes there is also a base coolant system oring that gets installed when dropping on the cylinder, be sure to replace that one and any other cylinder seals and gaskets, simply leave nothing to chance. And again not looking or studying my new 300 machine, there were coolant passages onto the forward PV plate assy on my old 250/300 if I remember correctly.

PS Evans/ZipTy XF1 and XF2 does expand a little bit so if you are topped off you will see some come out from the system, I keep mine just above the top row of radiator passages, so there is an air gap to the fill port. WHen I topped it and capped it I got some leakage and thought I had an issue, it just dumped what it did not want and stabilized above the passages.

PS with this non-aqueous stuff you can go MX race bike style and just have a dump tube with no catch tank.

Like stated above pull your cylinder and do all your seals and gaskets, if you don't or cant get dialed on your base gasket thickness its safer to be thicker (lower comp, larger squish band , no worry about port degree timing at this level). I always drop the cylinder on and cycle the piston and make sure it matched the visual evidence mark or just slightly below to allow for the torque squeeze from final assy.

[blakeNY9 0]

Thanks guys. Since I am impatient with these kinds of things I just ordered all 4 base gaskets and will match it to what's installed when I get it apart. It was only an extra $12.

O-rings, top end gasket kit (incase anything doesn't come apart well) and new piston rings on the way.

[mtnmanseth 0]

Bingo, buddy, so far so good. Use a micrometer to measure the existing base gasket(s) and reinstall the new stack dry - differing opinions on that, but I found some solid logic that dry is better. With only 50 hours on the piston, you're not even half way through the life of it (as a fellow putt putt trail rider), but replacing the rings is definitely worthwhile. Inspect the cylinder walls for any nicks or scarring, scrub it down with WD40 and scotch bright pad, wash with soap and water. My biggest concern is whether that helicoil repair is holding. If not, you're only out a small investment so far, so we'll see how she holds after all new seals and gaskets. I just did all this on the GasGas, so I am happy to help, but tntmo and Spaugh are far more experienced than I.

[Chad 0]

FWIW, my experience is similar to robertaccio's... I switched to Evans in my 2012 350 XCF-W +/- 9 mos ago. Ran the prep and followed all instructions for using the Evans. Refilled the cooling system to KTM O manual spec., ran it a bit and checked the level, made sure it was to spec. (Note: I also replaced all rad hoses with Samcos with a thermostat delete.)

On my first ride, the rad cap overflow started dripping almost immediately (but I wasn't sure that was the source at first). I had suffered a pretty bad rad hit before switching to Evans, so thought that might be the source. The Evans exiting the overflow (some running down the frame where the overflow hose connects) and burning on the exhaust header had a very distinct smell (not to mention the noxious steam coming off).

When I got it home, I carefully checked all suspected leak spots and determined that the only "leak" was from the overflow at the rad cap running down into the frame (as normal).

Each time since where I've topped it off to spec., I have the same experience (similar to robertaccio's). The Evans will "expand" and push out the rad cap overflow until it "self equalizes," then everything appears to be fine. Bike doesn't seem to run noticeably hotter. Just seems to want less Evans.

I'm not chemist and have done little additional research on this, but if Evans is more "expansive" that a water / coolant mixture, perhaps the extra expansion is all that is hitting your overflow recovery and slight seepage / leakage on the exhaust causing the smell?

Might be too simplistic in approach, but this has been my experience. Thought it might be helpful. With that said, I have worried that I have bigger issues related to the cooling system, so maybe I'm missing something major. But once the cooling system "regulates," everything appears to run / function fine.

Hope you get it worked out easily!

[robertaccio 412]

PS on a side note,,,get some good replacement long hoses for all your overflow/drain/vent lines and run them all the way down under the engine so they pollute the ground and not get all over your frame, engine, bike in general and or burn on the exhaust pipe.

[blakeNY9 0]

Chad... Thanks for the thought. The problem has been same between regular coolant and the waterless Evans. I too have experienced the overfill and then overflow etc. I am now always sure to fill just above the fins and not higher.

I prefer to have the recovery tank as it catches what comes out in case you need it out on a ride. This was the only thing that abled me to limp out of the Tecate Enduro (as there was no pushing it out and towing would have been near impossible, only way out was to ride the terrain) . I had just enough coolant in the recovery tank (plus the water left in my camelback) to put back in the system for at least little cooling effect after I zip tied the system back together that is.

I'll be doing what all have suggested and report back on findings.

[blakeNY9 0]

Update...All bolts of the cylinder head cover and nuts of the cylinder base were torqued to spec. I have removed the cylinder head cover, the two O-rings were pretty hard and stiff. The base gasket appears to be intact. Here's a few pics:

Top of the cylinder where you can see dots of coolant inside of where the inner o-ring sits.

Looking down the cylinder after I removed it, as you can see lots of dots of coolant on the sides of the cylinder.

I had just washed the bike and run it up and down the street. The coolant system had been pressurized enough from the combustion chamber to push coolant to the overflow tank in that short time. Then, once shut off that pressure seems to push the coolant into the combustion chamber. This is consistent with buddies smelling coolant in my exhaust at start up when on the trail.

Piston and cylinder look pretty good with 50 hrs on them. I will be replacing the O-rings on top of the cylinder, the piston rings since I'm in there and the base gasket. I also redid the exhaust flange O-rings and sealing for those coolant passages as well. Hopefully this will solve my issues!

Of note... the base gasket that came off currently measures .65 mm. My two options for replacement are a .5 mm and a .75 mm. So the one I took off, is it a .5mm swelling from moisture to .65 or a .75 squished to .65?

[mtnmanseth 0]

I don't know. The safe route would be to run a single 0.75. Or, do a squish band test with lead core solder after installing the 0.50 to make sure the top of piston to head clearance is acceptable (~1.2 - 1.8 mm I believe, but verify this). If the original 0.65 base gasket is made out of plastic, you could eliminate the swelling theory. If it's paper/fiber, then swelling could be possible given exposure to coolant (on the inside only) and probably be fine with the 0.5.

I pulled a single 0.3 mm paper base gasket out of my GasGas during my top end replacement, then accidentally tore the replacement 0.3 mm paper gasket during reinstall. I had purchased a plastic 0.5 mm base gasket too, and just to get it done (and being impatient) I just ran the 0.5 mm plastic gasket instead, thus increasing my squish by 0.2 mm. However, I performed the solder test with the 0.5 mm base gasket installed before sending the head for machining, so it didn't matter anyway (for squish band - it did change exhaust porting timing by 0.2 mm... oh well).

So... to answer your question... I guess I'm not experienced enough to tell you whether unintentionally increasing your squish and exhaust port timing by 0.1 mm by running the 0.75 would change the tune of your motor at all. I doubt it. I would scour the KTMTalk and Thumpertalk forums, or email Ron @ RB-Designs. Paging Tom, Spaugh?