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KTM RC390 | Investigating the cooling system | Hopefully not a blown head gasket!

Getting familiar with the RC390 and trying to determine if it’s got a bad head gasket.

Hey guys welcome back to the rc390 project where i started taking everything off of it and taking a look inside see what we can find out about the coolant issue you can’t see a lot from the outside the coolant level is like super small and i don’t want to be around with it so we’re just gonna rip everything off all right we’re gonna start up front and move our way

From top to bottom getting the mirrors off the windshield and then starting with the bodywork back here some hefty mirrors this is all metal up doing here alright so my plan is quickly unfolding the windscreen mount or one of the windscreen mounts is down here so i have to actually take the fangs off first and there are five super convenient to get these lovely

Little plastic pops yeah there’s two on the inside holding the radiator garden these are those little pop rivets as talking back so there’s one here should be one here and there’s one down there and then you choose the four millimeter allen key push to the center and you should be able to use a little screwdriver to pull it out let’s get this light bar off it

Is ingeniously connected with some zip ties this thing must have been pretty floppy at speed i mean at least it’s light but dang that’s all that’s holding that on there a brave man oh great let’s just pull out yep there we go i mean decent connection so at least it’s not like just kind of run into clip the wires sweet looks like this cow just held on buddies to

The little pop screen honestly i have no idea what these are called but they’re on like every single automotive vehicle ever ever is a little pushing clips whilst a clip on each one sweet alright i’ve been looking at this belly pan for a second it looks like there’s two these five mils of front hormones more bells up front and i think there’s a hidden metric

Eight socket under the engine it’s like ever so small ever so short all right in my infinite wisdom i neglected to notice that the bracket was actually holding onto the two allen heads that are in the back so didn’t need to do that at all that’s cool it’s off to reattach that it’s about to drop off i think so genius me took off the bolts for the actual bracket

Here focus i took this bolt out on each side being like oh yeah that will help it come out yeah there’s two allen keys through here they’re just mount to the bottom of the tray so way to go me all right i retighten the belly pan bracket i’m gonna take the tail off as well starting to look a little bit better for working on all right with the bike down that

Side stand we can kind of see that the coolant actually falls right about at the minimum line so i’m gonna fill this up to max and then we’re gonna run for a little bit i’m gonna throw a piece of paper under the bike and see if i can see any leaks anything obvious if not then we know we need to dig a little deeper so ended up overflowing it just a touch we got a

Little bit out of the overflow tube so i’m gonna clean that up and then will run the bike make sure we’re not squirting out anywhere else so i got a nice piece of butchers paper under the bike so if any fluid spill i’ll be able to see it really easily the other things that i kind of want to look out for are any smoke from the exhaust and any cloudiness in this oil

So right now it’s looking pretty good you can focus i mean this way looks brand-new so if we see in cloudiness in that well know that the oil and coolant mixing and make sure that the coolants not getting oil pushed into it so those are three three things we’re gonna check out while we run the bike up to operating temperature and maybe a little bit higher see if

We get it a little bit hot so i didn’t see anything coming out of the exhaust well looks mm-hmm looks fine it’s about the same as it did before and there’s nothing on the paper below so we might have to do this a few times cycle through the engine heat i’m not gonna do it tonight it’s actually a little late i’m sure my neighbors are loving this but yeah well cycle

Through this see if we get the cool to keep burning through otherwise i don’t know maybe it was just a fluke overheating incident a dump coolant on the previous owner might be in luck might not have to pull this engine apart so i’ve put a few heat cycles to the ktm and as far as i could tell that coolant isn’t moving i’m not seeing any leaks there’s nothing going

On with the oil i did drain off a little bit it looked like the level on the oil was a little foam and after reading the manual you’re supposed to check it when the bikes warm so i let the bike warm up check the level a little over full i drained some and this is what it looks like we’ve got a nice green color here but what i did notice is there is a slight line

At the bottom of this now this could just be sludge falling out of the oil but it also kinda looks like coolant so i’m not exactly sure see i’m not sure about the oil situation the coolant level hasn’t dropped at all my next plan is to take it for a short rip around the block see if the coolant goes down under high load or you know higher rpm so not too long a

Rip just kind of real short and i’ll probably film that just to get my first impressions from riding the bike i really haven’t ridden it since i picked it up yeah i think that’ll be it for this one thanks for hanging out with me in the garage i’ll see you on the next one and please leave a comment down below if you have any suggestions for kind of seeking out this

Head gasket issue i figured it would be really easy to spot it’s been a little difficult but thank you again if you want to check out more videos from me hit that subscribe button like this video if you liked it if not leave me some comments tell me what i can do better peace

Transcribed from video
KTM RC390 | Investigating the cooling system | Hopefully not a blown head gasket! By Garage Addiction