Whoa! KTM 790 Adventure R coolant leak fix. I was not expecting these issues.

[@Windblown]

The original housing was redesigned. I agree that the original was a bad design. You kind of shot yourself in the foot with the bolts. The new thermostat housing calls for a shorter bolt length. Re using the originals is what gave you the headache. KTM hose clamps are about as good as you'll find on any motorcycle though they are a bit on the thin side. They have rounded edges to prevent the clamp from cutting into the hose which is something cheap clamps don't have. ABA/Scandvik hose clamps are of the same design as OEM but wider and thicker and completely stainless steel. I use them and they work great. Glad you got it sorted!

[@TJGoober]

Jeremy, good video, thanks! FWIW, I had leaks on two coolant hose ends on 2019 790R. The one behind the radiator, on top of the headers, is impossible to see without removing the radiator and it appeared to have leaked since new. I tightened, replaced one clamp on the water pump end and even added a second hose clamp there with no success. No issues w/ the T Stat housing though. If you are going to this much trouble (removing the radiator) chasing leaks get a set of the Samco Silicon hoses and their heavy duty hose clamps. Absolutely worth the money and solved my leaks and a robust upgrade. Note the torque spec on their hose clamps, it is a lot tighter than I would have ever tightened them. Cheers!

[@Docv400]

Threads are cut with a Tap, so running one down again won't damage them in any way (use a 'Plug' [Bottoming] Tap). You're more likely to damage them with a DIY-grooved Bolt, as there will likely be Burrs along the Groove(s).

[@hojresor]

Good video. I just found out that my KTM 790 Adventure R leaks on the thermostat-house, just like yours did. I bought my KTM new in the spring of 2019 and the first week or so I had to tighten the hose clamp on the thermostat-house, because it leaked. It stayed dry until last week when I have driven it 30,000 km.

[@zoeylamant8298]

pls keep us updated. ive done the samco hose upgrade just to realize the leak is coming from the thermo housing just like you. these design flaws seem like rookie stuff for such an experienced manufacturer. hard to get help with it on the ground as well. smh, real frustrating .

[@TheOliveradams]

I recently also discovered a few drops of coolant under my 890 duke R (10.000Km) , I just fastened the clamps a bit more and the problem was solved 😃

[@nortnad138]

Finally, a video which explains it all! Good job. Thinking of laser cutting an aluminium spacer, instead of making a gasket? Or should it be malleable?

[@Howling-Mad-Murdock]

Hmm, interesting. Good vid, looking forward to seeing if you get a response from KTM. I’m guessing something is amiss, because if that’s the part they are using now, then surely they’d all be impersonating a steam room from new.

[@davidazzano5520]

I own a 21 KTM Adventure R and brought it in for its first service to a KTM dealer. After words my bike was leaking? They overfilled my oil and said they could not find the leak. I brought my bike home and started to investigate the leak. I found a coolant line with a loose clamp. Tightened the clamp no more leak. You would think the KTM Dealer mechanic could have found it? Not plus know not to overfill the oil. Very disappointed in the KTM service.

[@sadeqalbana]

sir you saved me a lot of time, I have found everything I need in a single video, much appreciated. what about the oil leaks from the cylinder head, you seem to have this problem too, have you just gave up on fixing it because it keeps on returning?

[@jlmainusa]

Hello. Glad you found this helpful. I haven’t had oil leaks though (on this bike at least). My KTM 350 has a small leak when it’s ridden hard. But the amount of oil lost is so small I don’t worry about it.

[@Northmanbimmer]

Hello, I live in the north of France and I'm glad I saw your video to fix my fucking leak! Thank you very much for sharing your experience with lots of details and part references. ✌🏼

[@dominiqueroumieh9260]

Hello. Thank you for this great video. Hope that you can help me. I have a 2021 890 adventure r and it's leaking coolant very slowly, by night and from the same place as yours did. I saw your video and I am afraid to dive into my bike like you did. Are you a mechanic ? How much time it took you to remove all these parts and to put it back? Is it hard? Can't be done without removing the fuel tank? And last, the solution is to replace the water connector or to add a ring inside to tighten the connection ?? Thank you in advance for your reply.

[@jlmainusa]

Hey Dominique. Thanks for your message. It’s not difficult to repair but it does involve removing the tank and draining the coolant. If you plan on riding off road, you will probably want to learn how to access and fix your bike in case you have a problem on a trail. Having said that, I would recommend you ask a friend (who is comfortable mending machines) to help you fix this issue. Good luck 👍

[@dominiqueroumieh9260]

Thank you again. I completely agree about repairing your bike. In fact, I only ride off-road. However, I am studying my options. Maybe, I will leave it for winter and I take my time on it

[@jakedickinson]

Working on a KTM is like building a kit car.

[@garysramblings8584]

Hi Jeremy, I've been looking for a lighter off road bike and this KTM has been on the shortlist so I watched with some interest as you might imagine. I'll be interested to hear what KTM have to say, as I know from previous examples where item have been changed, that it often isn't just one item that is effected. The lower profile of the thermostat housing cover might also need a different thermostat and shorter bolts as part of the change. It takes a good switched on parts guy to make sure that you are aware of the big picture. As a case in point two friends had their compensators fail. One dealership gave one price the other the dealership the price was three times the amount. The first was just going to supply the compensator, while the second knew that the new up graded compensator needed a new alternator to go with it, due to the increased size of the new item. So it really could just be the stores person didn't know their product.

[@jlmainusa]

Hi Gary. The 790 R is a fantastic bike. I rode 9,000 solo around the TransAmerica Trail last year and this bike was phenomenal - comfortable, handed beautifully - perfect. I dropped it several times and I knew I would be able to pick it up and recover without issue (including the time I rode through a stream and wheels sunk up to the axles!). This coolant leak was trivial and I could have lived with it. I'll post KTM's reply.

[@garysramblings8584]

Hi Jeremy. Thank you for getting back to me. I'll definitely be having another look at the bike when the weather improves and the lock down eases. Space is an issue at the moment too, but I'm getting that sorted soon. I could always sell one of my other bikes, But my new Rocket 3 GT is a keeper as is the BMW GS which I do take off road, but that can prove to be a real workout if you have to lift it out of the mud more than twice. I'll look forward to hearing the update, and thanks again, ride safe.

[@checkitout3474]

Hi! Thank you for sharing your experience. I have a 2023 ktm 890R. After one year of ownership and 5600 miles on it, I noticed that the coolant level I slightly under the min (I checked it with the bike on the side stand). I have not noticed any leaks on the floor. During summer where I live we get to 100-105F. I have two questions: I) is it possible to lose some coolant as a result of riding in high temperatures? Ii) the coolant that have now is clear (it is the OEM), however, the manual recommend the Motorex M3.0. Do you think I can top it off with Motorex, and therefore mix it with the original one? Thank you!

[@jlmainusa]

Hi. Interesting question. Coolant is cheap so I replace every year. As such i haven’t seen the levels drop. I run my bikes on Evans coolant which doesn’t corrode the inside of the engine and it can cope with high temperatures as well. Hope this helps.

[@checkitout3474]

@@jlmainusa Thank you for the feedback! Is the process to replace coolant complicated? My concern is about trapped air bubbles. It would be amazing if you could do a video for us on how to do that!

[@craigwac5567]

Hello Jeremy from KY. You video is perfect. My clamps were loose too. I would like to get the clamps you used. What brand part number are they? Where did you purchase them. I like the idea of the spring for constant tension through the heat cycle.

[@jlmainusa]

Hi Craig. They are on Amazon: Oetiker 17800175 Stainless Steel Self-Tensioning Steples Hose Clamp, Bolted, 9 mm Band Width, 30 mm - 36 mm Hose OD Range (Pack of 10)

[@andreglomm9843]

Nice

[@nesmrtelnateta]

interesting...well it seems it all worked out in the end, i dont know if it is all companies or just ktm that bikes have so many baby problems or what is it called in english i have 2020 model so i hope im all sorted out, i had one mist or cloud of coolant leaking but never showed again so i didnt bother to investigate

[@Marillionado]

Great indepth video. Thank you very much indeed.

[@josepinofpv3233]

Hello Jeremy, your video is awesome, any chances you remember the dimensiones of the ring sealing element yo put in the thermostat?

[@josepinofpv3233]

And do you have any update fo the leak? was it an final solution?

[@jlmainusa]

Hi Jose. Thanks. After fitting the seal, I have not had to touch cooling system. No leaks 👍. I can’t recall the exact dimensions but it’s easy to measure when you remove the thermostat cover. I used gasket material that was about 1mm thick. It was “donut” shaped and around 3mm in width between outer and inner circumference. Hope that helps

[@josepinofpv3233]

@@jlmainusa you are the best my friend, thank you!!!

[@ydocsaee421]

Hello. Just watched your video, and just want to say, great info! I have a 2021 890 S and I'm having a small coolant leak upon cool down overnight. Apparently it's still an issue. Any specific way to confirm if it's the housing with the thermostat or just a hose, without pulling it all apart? What's the best way to get one of those custom gaskets if needed? Thanks for your info.

[@jlmainusa]

Hi Cody. My housing has been watertight since I made that gasket. KTM have released several upgraded manifold housings and I would have thought the 890 would be problem free by now. I made my gasket by buying sheets of gasket material and cutting my own with an x-acto knife. I wouldn’t use gasket cement from a tube Hope this helps.

[@gregheth]

Thank you. You saved me hours

[@janeelp]

I am having a similar issue with my KTM 890 Duke R. I was doing some research and came across your video. With regards to the bolt issue, I noticed in the video that the older housing had thicker shims built into the housing. Very similar to the washers you installed. Did you check to see if those were removable and could be swapped over to the new housing?

[@greatfallskam]

Hi Jeremy, Looks like you have one of the few definite videos on how to permanently fix the KTM 790 / 890 Adventure / R coolant leak. Can you tell me of those OETIKER clamps you're using open up to go around hose without having to remove hose? Do you have a detail video or resource on how to take radiator off? Oh. What was actual diameter of hose going to the thermostat housing? You mentioned you thought some of the OETIKER clamps might big too big. Thanks. Kam

[@jlmainusa]

Hi Kam. All good questions but truthfully I cannot remember all those dimensions. I've included a link to a manual that I think will help you: www.dropbox.com/s/iyxf3k3jugs7kit/KTM%20790%20EN%20Repair%20Manual.pdf?dl=0

[@andreglomm9843]

My 2019 R I Just buy used in November leaks also I Hope the Sales Dealership will repair it. But have u a Update? Still no more leaks?

[@graysonchurch262]

Great vid! Love it when people find well thought out simple fixes. The thousand dollar question... what do you think of the 790 and if given the choice, would you buy it again? I’m about to buy either the 790 or a t700 ( with full suspension upgrade ) so both bikes will be of equal value, so hopefully I’ll be comparing like for like. Just wondering on your honest thoughts from a mechanical perspective on the 790r and the ease of which you can maintain it yourself? I’ve previously owned a heavily modified 990r which I really liked as I found it relatively easy to take apart with very basic tools. Would love to know your thoughts?

[@jlmainusa]

Hi Grayson. 790 is a fabulous bike. But it’s been replaced by the 890 which I’m sure is equally as good. I would definitely recommend the “R” model. The electronics and adjustable suspension are fabulous. I haven’t ridden the Yamaha, and it sounds great value for the money. But I’m sticking with KTM because I ride offroad as often as I can.

[@mahuro001]

What diameter does the thermostat have to make the gasket?

[@TheDavidGoldmanphoto]

Well, this was VERY helpful!! I'm curious if you have now modified and put on the 63535019200 part? I have a 2019 "S" version and it's been leaking. All the clamps have been tightened but still happening. Seems likely this is the culprit.

[@jlmainusa]

Hi David. Sorry to hear about your leak. I only did exactly what I showed in the video. New coolant connector (with home made fiber gasket). Washers under the connector's bolts, and the new clamps. She's been water tight for since then. Not a drop lost 🙂

[@TheDavidGoldmanphoto]

@@jlmainusa I looked into the new piece and turns out it's back ordered till Dec (at least in Nova Scotia, Canada) I'll be coming to the UK next month. Maybe I'll swing by your house ha ha :) Thanks again. If you are at the ABR maybe I'll see ya. I'll be presenting photos from my series. The Motorcycle Portraits.

[@jlmainusa]

@@TheDavidGoldmanphoto Hey David. I would experiment making that gasket and use the existing connector (with washers). I suspect that will be a big help. I'm in Las Vegas now. Both a basic and ADV rider instructor. Great to grab a beer if you are in town. Cheers

[@TheDavidGoldmanphoto]

@@jlmainusa A, Vegas. I passed through there two summers ago when it was 118 degrees on my way to LA. I'll keep it in mind. Thanks again.

[@maariog.3801]

ktm changed the water connection part number 63535019100 =>63535019200. Maybe you don't need to add a thermostat pad anymore

[@andreglomm9843]

Thanks for the Info

[@tylervosters3234]

What lights do you have mounted to your forks and how did you mount them

[@jlmainusa]

They are Denali DM LEDs. I have on all my bikes. Very small but very bright. I mounted them on the two arms that KTM uses to support the headlight. This allows lights to stay pointed straight ahead even with the front wheel turning

[@jshingler5284]

Good video. Couple thoughts. Is the new replacement part thinner at the bolt flange? If so could have just shortened the bolt a couple threads. I am wondering with the new part you should have gotten a thicker O ring. That may have been superceded too. Either way you got it fixed. 👍

[@jlmainusa]

Both flanges are the same thickness. I decided not to cut the bolts as I'm never sure if they are plated or solid stainless. I've pinged KTM and asked for comment.

[@alexballery3753]

Hello, thank for the video. I think i have the same issue... Was your bike smoking sometimes in the morning when you start it ? Was it leaking on the manifolds ? Thank

[@jlmainusa]

You will probably smell a sweet odor. That’s the coolant as it burns off on the exhaust. You’ve probably got a small coolant leak. I would stress. Keep an eye on your coolant level and top up, or replace flange per my video. My bike is as tight as a duck’s ass - and that’s watertight 🤣

[@edwardflavin2398]

Where did you purchase the hose clips ? Thanks

[@jlmainusa]

Search Amazon for "Oetiker Stainless Steel Self-Tensioning Hose Clamps"

[@aleksandartasic7652]

There is no way that is a correct replacement part. No way engineers will be that far off. I suggest you check your part numbers for compatibility.

[@MichaelM-to4sg]

Completely agreed. It’s possible too that the new spigot requires a new thermostat which has a perimeter shoulder and/or thicker o-ring. If this were in fact a straight part replacement from factory, this issue would have been identified immediately. This is clearly dealer parts dept that is clueless. Your video should be titled “My dealer parts dept sucks” not anything applicable to an engineering problem at KTM.

[@TheFastphill]

@@MichaelM-to4sg my Guess is KTM make a 890 and pretend the 790 never existed

[@adamstallard5523]

Hi Jeremy, having the exact same issue as we speak. Do you remember what material you used to make the gasket out of to put under the thermostat? Thanks

[@jlmainusa]

Hi Adam. I went to a general autostore. They sell sheets of gasket materials in various materials. I forget what I used but it felt like a rubbery felt. It was around 1mm thick. Hope this helps.

[@wardiup939]

Such a great video! So thorough 👌👌

[@tonygreen8221]

With all due respect Jeremy, I don’t think you should be making engineering judgements given that you didn’t immediately identify that the original part was a different moulding to the replacement . The bolts being “too short” should have also rung alarm bells that something wasn’t right. There’s always a chance of human error in the parts supply chain and as home mechanics, we need to be on the lookout for those things. Agree that original clamps aren’t brilliant, but if not over tightened, they’re good enough and those clamps that you’re putting on are a more complex design and frankly I don’t see the need for a hose clamp to expand with heat or contain a spring. Will be interesting to see how they hold up. Lastly, I think that adding that large spacer next to the thermostat is only asking for trouble. I think you’ll find that with all the correct parts, things will go together nicely. Thanks for making the video. Interesting bike.

[@jlmainusa]

Hi Tony. It is a head scratcher. I have asked KTM for comment and to clarify if and where I made a mistake. My experience with KTM is that they use the same part number in as many bikes as possible. Makes sense because designing, manufacturing and storing etc is expensive. So why would they make more than one flange that are almost identical. I doubt they would. And in any case, both flanges were the same depth, so bolts bottomed out on both. Anyway. I'll post KTM's reply. Good thing is my persistent coolant leak has stopped. Excellent!

[@zerocochrane1713]

Hello, technical question. What sealant (some loctiete?) did you use with thermostat housing? What sealant did you use ?

[@jlmainusa]

Hello. I didn’t use sealant. I bought a pack of gasket material sheets from local auto store. I made a circular gasket to fit housing. No need for sealant. No leaks after several years 👍

[@zerocochrane1713]

@@jlmainusa thanks for the reply, regards !

[@maariog.3801]

how tightly to tighten the screws of the thermostat housing

[@jlmainusa]

Hi Maario. The manual says 6NM

[@zipsfranquemont7104]

Any updates? Incorrect part? Comment from KTM?

[@alfonsomarquez4445]

Hi Jeremy I have the same problem, but instead of adding a gasket I’m going to mill de plastic part, I’m going to remove .015” (.40mm) . Question, how thick was the gasket that you install ? And the leaking stoped?

[@jlmainusa]

Hi Alfonso. I've had the gasket in now for 18 months and it still works great. I think I used 1mm (1/32") sheet of rubber/cork gasket material. Cheap at most vehicle supply stores.

[@alfonsomarquez4445]

@@jlmainusa 😉👍thank you !!!! Great video !!!!

[@gregheth]

Thank you

[@arthurleithold2290]

What are the gasket dimensions for the one you made if I may ask? And out of what material?

[@jlmainusa]

Hi Arthur. I bought a general pack of automotive gasket materials off Amazon. Packs are cheap and have five or so squares of different materials and thicknesses. I don't recall the exact thickness, but it was a rubber-fiber -like material. I think it was either 1/32 or 1/16th" thick (the thinnest option). BTW: My bike has run flawlessly since fitting it. No issues whatsoever.

[@yvesdegheselle]

Thanks for this excellent Video

[@ben333river]

Nice work!

[@mahuro001]

And what type of material do you use to make the gasket?

[@jlmainusa]

Just pop down to an auto parts store and they sell packets of gasket material. Usually has a few different materials in each packet which allows you to choose the right one for the job.

[@mahuro001]

@@jlmainusa Thank you very much, look and see if I can find it

[@RollinwithRoland]

Great video, I'll definitely be keeping an eye on my 2019 790S now. Just bought a month ago and at 2200 miles. The only issues I've had so far were the result of some shitbag technician assembling my bike with not a torque wrench in sight. Had a mirror come loose at 80mph, had my shift linkage come loose at the top were it connects to trans... then, one of my hand guards popped loose at 75mph...

[@jlmainusa]

I heard the same and went over my bike with torque wrench. Had the same shift linkage issue. Once you've done that, I suspect she'll be perfect.

[@RollinwithRoland]

@@jlmainusa I brought it back to the dealership I bought it from after having the first service done 3 weeks ago, I made the service manager very aware of the issues. Brought it in specifically for checking torque on EVERY nut and bolt... Rode it 130 miles across the state, and they bring it back out "done." I gear up, go to put it in gear and the shifter sticks down... Upshift, sticks up...moron over-torqued linkage assembly.😠🤬🤬

[@ericdawson3425]

I bet you don’t hear from then maybe you should have got a new thermostat with a newer rubber gasket at the same time you got the new housing

[@torevenheim9607]

Use plastic parts in cooling system is not a good thing, it will rot and warp with age

[@queenslander954]

After seeing all the cheese camshafts videos , I’m thinking coolant is the least of your problems.

[@jlmainusa]

I’ve had my cams checked. All is okay 👍

[@jimh2061]

Did this solve the coolant leaks on this bike. I'm thinking about doing this too.

[@jlmainusa]

Yes it did. No leaks since then.