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Can overfilled oil cause overheating? (and am i likely to have done any other serious damage??!)

• bought a 2nd hand PCX125
• did first longer ride (40kms), no prob on the way there. bike stood outside all day (temps in the 20s celcius), and then drove back. about 10min into ride back, red temperature warning light came on.
• pulled over, let bike cool down, and then rode slowly to garage. saw that reserve tank was empty so bought some mineral water to fill it. only needed about 150ml to fill (to slightly above upper level mark actually), so since manual says it's 0.7l cooling syste capacity, it couldn't have been completely dry (right?!).
• light came on again after another +-10mins, rode home slowly, stopping now and then to allow engine to cool down before riding on
• have since siphoned out mineral water and replaced with 50-50 coolant
• also discovered that prev owner had over-filled oil - dipstick measuring point is about <1cm, while oil level is about 1.5cm at least above that! don't have torque wrench, so didn't drain any oil yet.

After that first long ride 3 days ago, I also did the following:

• On leaving bike idling, temp warning went on after about 25min. (zero throttle, just idling)
• Driving about 5kms each way last night (cool outside temperatures) had no issues.
• This morning, <5kms driving, about 2kms on a highway at 100km/hr, and i felt engine lose power. Pulled over, and even before i'd stopped completely i felt it pick up again so pulled off again. A few seconds later, temp light came on again. And then as I stopped at a traffic light to get off the highway, the bike cut out completely as I stopped. Pushed it into some shade, sat for a few mins, and was able to start again and ride slowly home - though it cut out again at a few traffic lights, and i also had to pull over once after the light came back on.

Could the overfilled oil be the cause of the overheating and the loss of power and then cutting out at the traffic light??
Am I likely to have caused other issues through my riding/tests as described above?

THANK YOU IN ADVANCE!!

Overfilled oil can possibly cause damage to seals, but that isn't a huge amount of overfill. It sounds like the problem is with your cooling system. The only way there should be contamination of the cooling system by engine oil would be through a blown seal or gasket, but you'd have other symptoms as well.

The issue is most likely in the cooling system. The fact that you needed to put so much coolant into the tiny little system on the PCX is enough to raise my eyebrows. 150 ml may seem like a lot and would be on any car engine, but for the PCX, it's a huge amount.

It may just be an air bubble somewhere in the system, or it may be crystals blocking coolant movement. either way, I'd have the cooling system checked.

You'll only get very high temp if you have less oil in your engine, but not if you overfill a little. It's probably a prob with the cooler as what honkerman is saying.

Thank you to both of you for your responses.

Just to confirm if I didn't make it clear -- the oil is level is about 1.5-2cm above the usual high level mark. So where the dipstick high mark is at about +-0.5cm, the level is at 2-2.5cm. When I checked it this morn, the oil had actually also come up into the wider area where the screw threads are for the dipstick cap. Would you still classify that as "not a huge amount"?

I'd read some posts as I looked around for solutions on the web of people who had also noted high temp warnings after they'd overfilled by mistake (mostly related to cars tho!). That's part of what had made me think it might be related to that...?

I don't think the previous owner ever drove further than a few kms at a time, so my thinking was also that though he'd overfilled, that perhaps the issue only presented itself after I'd taken the longer drive which had allowed heat and pressure to build up a bit more.

My guesses are based on googling and surmising tho - I'm definitely no expert!

Agree with above, this is a cooling problem, not overfill of oil. And go ahead and drain a bit using a turkey Baster, or the drain bolt, cinch it 1/8 turn after tight, use the TQ wrench later.....

megb wrote:Thank you to both of you for your responses.

Just to confirm if I didn't make it clear -- the oil is level is about 1.5-2cm above the usual high level mark. So where the dipstick high mark is at about +-0.5cm, the level is at 2-2.5cm. When I checked it this morn, the oil had actually also come up into the wider area where the screw threads are for the dipstick cap. Would you still classify that as "not a huge amount"?

I'd read some posts as I looked around for solutions on the web of people who had also noted high temp warnings after they'd overfilled by mistake (mostly related to cars tho!). That's part of what had made me think it might be related to that...?

I don't think the previous owner ever drove further than a few kms at a time, so my thinking was also that though he'd overfilled, that perhaps the issue only presented itself after I'd taken the longer drive which had allowed heat and pressure to build up a bit more.

My guesses are based on googling and surmising tho - I'm definitely no expert!

I'm curious as to whether you are checking the oil correctly. The proper technique is to unscrew the cap, wipe it off with a clean non-shedding towel or paper towel, then stick it back in without screwing it in at all, then pull it out again and read the level. If this is what you're already doing, then yeah, siphon out a bit or drain it with the plug. Still, your issues would include bogging, oil in the throttle bodies and smoke out the exhaust, but not anything with cooling as the two systems are not connected.

honkerman wrote: I'm curious as to whether you are checking the oil correctly. The proper technique is to unscrew the cap, wipe it off with a clean non-shedding towel or paper towel, then stick it back in without screwing it in at all, then pull it out again and read the level. If this is what you're already doing, then yeah, siphon out a bit or drain it with the plug. Still, your issues would include bogging, oil in the throttle bodies and smoke out the exhaust, but not anything with cooling as the two systems are not connected.

Thanks honkerman. Yep, that is what I did. Did the full caboodle - let it idle for 3-5min first, then switched off and let it settle, and then checked the dipstick as you described.

Unfortunately my regular trusted mech is on holiday for a few more days, so I'll have to wait for him to get back before I can take it to get the cooling system checked. A little sad and frustrated - just got the bike 2 weeks ago, and after riding a cheap chinese brand before, this was supposed to be my trusty, reliable ride!

megb wrote:When I checked it this morn, the oil had actually also come up into the wider area where the screw threads are for the dipstick cap. Would you still classify that as "not a huge amount"?

Chief say's that's definitely not a small overfill, so yeah might have to classify that as huge. Perhaps even the biggest overfill on record.

Reminds me of a local story where a guy had a new hot tub installed and without reading or giving any thought to measure emptied the entire contents of every container given to him by the retailer into the tub and turned it on.

It does seem with that much oil in the crank the little engine could work pretty hard.

Just change the oil and see if the problem is still there.

You can't top up coolant by that top reservoir. You will have to take radiator cover off and undo the coolant cap there. Top it up let it idle and keep squeezing all rubber hoses you can reach blipping the throttle time to time. That will let all the air trapped in the cooling system.

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Oil overfill can kill an engine. Too much oil and the crankshaft will beat the oil up, making it thinner.

Your problem is coolant related. On a cold engine, open the radiator cap and add coolant. Don't try to use the scooter anymore because you may overheat it to the point of warping the cylinder head. Then it will be a very expansive repair

The oil and the overheating may or may not be related.

Drain some of the oil out and you will have addressed one problem. A large syringe and pipe or a meat baster will do it in seconds.

Then you can concentrate on the overheating problem if it is still there.

Not sure if this is BS - but I thought little amounts of oil, over time, end up in the lhs cover but the drain tube thing - perhaps if there is a great over-fill of oil lots has spilled out and is clogging that side of things. Just a thought, probably a bad one

Thank you everyone for your advice and comments. Really love the community support attitude. Makes me happy to be a fellow PCX'er

Here's the update --
If the 150ml of liquid I had to add to the reserve tank caused alarm.... wait til you read this: From the comments made above, I decided I could safely ignore the stern warning the owner's manual gives to NOT add coolant via the radiator cap, mixed up some 50-50 soln and glug, glug, glug it just kept wanting more. About 350ml in the end! As I let it run a little to work out the air bubbles, I saw a spot of fluid on the ground. Problem seems to be identified: the cooling system is leaking somewhere

I've heard Honda parts can set you back quite a bit more than others (at least that seems to be the word on the street in South Africa where I am) so I'm reeeeeally hoping it's just a pipe or something that my mechanic can help me fix.

Still didn't drain (or turkey baste!) the extra oil out yet, but I think I'll leave that to the mech as part of a full system check-up when I take it to him for the cooling system. Only 2 more days until he gets back from holiday.... taking all my self-control to respect his time off!

Though you may find it expensive for shipping costs from this site I am about to mention, you would be able to get an idea of costs of oem parts. Go to bikebandit.com and look up your bike. You will not find a 2013 version of the pcx 125 but you could try 2012. The objective is to get an idea of the costs. I am sure there are other sites that you can order parts from. This is just for your peace of mind.

megb wrote:Thank you everyone for your advice and comments. Really love the community support attitude. Makes me happy to be a fellow PCX'er

Here's the update --
If the 150ml of liquid I had to add to the reserve tank caused alarm.... wait til you read this: From the comments made above, I decided I could safely ignore the stern warning the owner's manual gives to NOT add coolant via the radiator cap, mixed up some 50-50 soln and glug, glug, glug it just kept wanting more. About 350ml in the end! As I let it run a little to work out the air bubbles, I saw a spot of fluid on the ground. Problem seems to be identified: the cooling system is leaking somewhere

I've heard Honda parts can set you back quite a bit more than others (at least that seems to be the word on the street in South Africa where I am) so I'm reeeeeally hoping it's just a pipe or something that my mechanic can help me fix.

Still didn't drain (or turkey baste!) the extra oil out yet, but I think I'll leave that to the mech as part of a full system check-up when I take it to him for the cooling system. Only 2 more days until he gets back from holiday.... taking all my self-control to respect his time off!

I wondered. Hope it doesn't cost too much. When you get the final verdict, please come back and let us know.

Get yourself an oil syringe off Amazon. It allows you to add oil an ounce or two at a time so you can get the level completely correct. On a PCX 150, put in in 22 ounces and then an ounce at a time until you're Dead center in the hashmarks of the dip stick. Don't be concerned about the capacity, or what the manual says to add, because you don't know how much was left in there , each time you add will be slightly different, getting it mid stick is the only way to be exactly correct. Here's one:

https://www.amazon.com/Pennzoil-31777-O ... il+syringe

I'm willing to bet it's a leaking o ring from the water pump. If not it's the coolant being boiled and flowing from the radiator to the excess tank.
Really hope it's not an expensive repair

Hello PCX-buddies!

Update on this....!

I was away for about a month, and left the scooter with my mechanic. He discovered that the water hose joint was cracked (prev owner had told me afterwards that they'd had it repaired rather than replaced because they didn't want to wait the 3 weeks it'd take the part to arrive). We ordered a new one and he replaced it.

Unfortunately the problem didn't go away entirely. Mech did a short test run (10kms, at 80-100km/hr) and the bike overheated again. I've taken back possession of the scooter, and while on most rides it doesn't overheat (some doing similar speeds and distances to his test ride), it has on 2 occasions - one was at the end of +-15kms, another was on just about 2kms on a hotter, windless day.

The mechanic wasn't 100% certain why it was still overheating after replacing the broken part, but his 'educated guess' was the following:

I suspect you have a head gasket problem caused from previous overheating, in turn due to coolant loss from the broken part, which of course we have now replaced, but you are now left with the side-effects of this. So I suspect that it has a blown head gasket and that there is warping on the cylinder head and that both the cylinder head and the barrel need to be skimmed and the head gasket replaced, you will probably need to replace the base gasket as well. (Head has warped because of the overheating and so gasket which is sandwiched between the head and the barrel is no longer making a proper seal. So replacing the blown gasket will not solve the problem until both the cylinder head and the barrel are given a light skim.)

It most certainly is still leaking coolant, which will be evident under load.
You'll probably need the head & barrel skimmed as well as head gasket replacement, to be on the safe side.

Unfortunately he wasn't keen to do the job, since he is going on holiday soon and he says it's a big one.
With the holiday season around the corner, I don't think I'll get another mechanic able to take it on until Jan either. And I need to wait 2-3 weeks for the head and base gaskets I'll order through Honda to arrive.

In the mean time.... any thoughts or advice?
About what the issue could be, but also if I'm likely to kill my scooter if I continue using it between now and Jan?? (If it overheats I immediately stop for 5min before continuing. Am building in a bit of extra travel time into my commutes to allow for it!)

Thaaaaanks in advance