Milwaukee Eight (M8) 2017 and up M8 Air and Liquid Cooled discussion
Sponsored by:
Sponsored by:

M8 problems

Thread Tools
 
Search this Thread
 
Old Apr 17, 2022 | 09:53 AM
  #2111  
1melted1's Avatar
1melted1
6th Gear
Joined: Aug 2013
Posts: 12
Likes: 1
From: Pickering, Ontario, Canada
Default 2018 M8 coolant issues

Morning,
please forgive me if this is not the place to ask this question and if it's not could someone please direct me. Thanks in advance.
Where's the problem?
2018 road glide ultra M8 from cold it will run for a short distance and overheat. Looked at the overflow jug inside the lowers and it was at the proper line before driving but once it got going, it filled the overflow jug to the top. Stopped and shut bike off then started water pump manually. The level dropped. Ran bike again and same things happened. Checked the pump and it does run. Checked the cap and its on properly. No obvious signs of leaking. Any suggestions?
thanks again
Steve C
 
Reply
Old Apr 17, 2022 | 10:06 AM
  #2112  
Quik's Avatar
Quik
Ultimate HDF Member
Joined: Oct 2016
Posts: 5,063
Likes: 2,582
From: On my bike!
Default

Originally Posted by 1melted1
Morning,
please forgive me if this is not the place to ask this question and if it's not could someone please direct me. Thanks in advance.
Where's the problem?
2018 road glide ultra M8 from cold it will run for a short distance and overheat. Looked at the overflow jug inside the lowers and it was at the proper line before driving but once it got going, it filled the overflow jug to the top. Stopped and shut bike off then started water pump manually. The level dropped. Ran bike again and same things happened. Checked the pump and it does run. Checked the cap and its on properly. No obvious signs of leaking. Any suggestions?
thanks again
Steve C
Is your motor laboring more than usual? Maybe pull the crank position sensor with the bike upright and see if you have excess oil in there.
 
Reply
Old Apr 17, 2022 | 10:22 AM
  #2113  
1melted1's Avatar
1melted1
6th Gear
Joined: Aug 2013
Posts: 12
Likes: 1
From: Pickering, Ontario, Canada
Default

The bike seems to run fine, no idle issues or starting problems. I'll have to look for the position sensor and see about checking there.
thanks
 
Reply
Old Apr 17, 2022 | 10:35 AM
  #2114  
Quik's Avatar
Quik
Ultimate HDF Member
Joined: Oct 2016
Posts: 5,063
Likes: 2,582
From: On my bike!
Default

Originally Posted by 1melted1
The bike seems to run fine, no idle issues or starting problems. I'll have to look for the position sensor and see about checking there.
thanks
Very simple check, 3/16 Allen bolt and just pull the sensor out, I would put a pan under it incase there is a lot of oil in the crank
 
Reply
Old Apr 17, 2022 | 10:45 AM
  #2115  
smitty901's Avatar
smitty901
Seasoned HDF Member
Veteran: Army
15 Year Member
Liked
Community Favorite
Joined: Feb 2008
Posts: 23,001
Likes: 11,441
Default

Go ahead and check for the sumping by pulling Crank senor. It hurts nothing to do so. This however sound like a water pump issue. Do the self test for fan and pump. Bet it is the pump. or fans
 
Reply
Old Apr 17, 2022 | 10:52 AM
  #2116  
Rounders's Avatar
Rounders
Seasoned HDF Member
Community Builder
Liked
Loved
Community Favorite
Joined: Mar 2021
Posts: 18,456
Likes: 3,723
From: backwoods
Default

Originally Posted by Quik
Is your motor laboring more than usual? Maybe pull the crank position sensor with the bike upright and see if you have excess oil in there.
I hope M8s are different than TC, that would be a lot of oil.

I read somewhere with TCs, to pull the drain plug on bottom end and measure oil to see if sumpin. Can you do that with M8s?
 
Reply
Old Apr 17, 2022 | 11:08 AM
  #2117  
1melted1's Avatar
1melted1
6th Gear
Joined: Aug 2013
Posts: 12
Likes: 1
From: Pickering, Ontario, Canada
Default

I'll try pulling the sensor for the crank. The fans and pump are working.
thanks again
 
Reply
Old Apr 17, 2022 | 11:09 AM
  #2118  
Quik's Avatar
Quik
Ultimate HDF Member
Joined: Oct 2016
Posts: 5,063
Likes: 2,582
From: On my bike!
Default

Originally Posted by Rounders
I hope M8s are different than TC, that would be a lot of oil.

I read somewhere with TCs, to pull the drain plug on bottom end and measure oil to see if sumpin. Can you do that with M8s?
Thats what I mean when I said pull the crank position sensor, I drained 60 ounces out of my crank when my bike sumped.
 
Reply
HD Forum Stories

The Best of Harley-Davidson for Lifelong Riders

story-0

7 Times Harley-Davidson Chucked Tradition Out the Window

 Verdad Gallardo
story-1

7 Surprising Harley-Davidson Products that Are Not Motorcycles

 Verdad Gallardo
story-2

8 Best Harley-Davidson Motorcycles Ever

 Pouria Savadkouei
story-3

10 Worst Harley-Davidson Motorcycles Ever

 Pouria Savadkouei
story-4

Killer Custom's Jail Break Is The Breakout That Refused to Blend In

 Verdad Gallardo
story-5

Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?

 Verdad Gallardo
story-6

Harley-Davidson Reveals Super Cool Cafe Racer Concept

 Verdad Gallardo
story-7

Engraved Rebellion: Inside Bundnerbike's Glam Rock II

 Verdad Gallardo
story-8

10 Motorcycles You Should Never Buy

 Joe Kucinski
story-9

10 Things Harley-Davidson Needs to Fix in 2026

 Verdad Gallardo
Old Apr 17, 2022 | 11:19 AM
  #2119  
Rounders's Avatar
Rounders
Seasoned HDF Member
Community Builder
Liked
Loved
Community Favorite
Joined: Mar 2021
Posts: 18,456
Likes: 3,723
From: backwoods
Default

Originally Posted by Quik
Thats what I mean when I said pull the crank position sensor, I drained 60 ounces out of my crank when my bike sumped.
TCs have a plug on the bottom. You can drain the oil and measure. 60 ounces is crazy

I am thinking of updating one of these years. I don't want to be a dinosaur. But one of my buddies says he has oil in exhaust, but doesn't care because it has a warranty. Myself I keep for years.

But the rest of it, and new stuff I want. Just the better saddlebags.
 
Reply
Old Apr 17, 2022 | 11:28 AM
  #2120  
Quik's Avatar
Quik
Ultimate HDF Member
Joined: Oct 2016
Posts: 5,063
Likes: 2,582
From: On my bike!
Default

Originally Posted by Rounders
TCs have a plug on the bottom. You can drain the oil and measure. 60 ounces is crazy

I am thinking of updating one of these years. I don't want to be a dinosaur. But one of my buddies says he has oil in exhaust, but doesn't care because it has a warranty. Myself I keep for years.

But the rest of it, and new stuff I want. Just the better saddlebags.
Yeah when that 60 ounces was in there the bike was laboring so bad it would barley pull itself, luckily I was only a couple miles from home. It sumped all of that after a 1st through 5th redline run through the gears, I knew immediately when I pulled out from the stop sign after that run what was going on, felt like wide open throttle with the brakes applied.
 
Reply



All times are GMT -5. The time now is 06:23 AM.

story-0
7 Times Harley-Davidson Chucked Tradition Out the Window

Slideshow: Harley-Davidson built its reputation on nostalgia, but every so often, the company took a hard left turn into the future.

By Verdad Gallardo | 2026-05-20 11:18:19


VIEW MORE
story-1
7 Surprising Harley-Davidson Products that Are Not Motorcycles

Slideshow: The bar-and-shield logo shows up on far more than motorcycles, some of the company's most unexpected products have nothing to do with riding.

By Verdad Gallardo | 2026-04-29 16:50:35


VIEW MORE
story-2
8 Best Harley-Davidson Motorcycles Ever

Slideshow: Not every Harley gets it right, but these are the ones that genuinely earned their reputation.

By Pouria Savadkouei | 2026-04-15 14:23:21


VIEW MORE
story-3
10 Worst Harley-Davidson Motorcycles Ever

Slideshow: From the troubled AMF years to modern misfires, these bikes earned reputations for reliability issues, questionable engineering, or disappointing performance.

By Pouria Savadkouei | 2026-04-01 20:01:09


VIEW MORE
story-4
Killer Custom's Jail Break Is The Breakout That Refused to Blend In

Slideshow: Killer Custom's "Jail Breaker" build focuses more on stance and visual aggression than mechanical overhaul.

By Verdad Gallardo | 2026-03-18 19:20:32


VIEW MORE
story-5
Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?

Slideshow: The Swiss custom shop has taken a Harley Softail and stretched it into something so long and low that it looks closer to a rolling sculpture than a conventional motorcycle.

By Verdad Gallardo | 2026-03-07 16:15:30


VIEW MORE
story-6
Harley-Davidson Reveals Super Cool Cafe Racer Concept

Slideshow: Harley-Davidson's new RMCR concept revives the café racer formula with modern hardware-and it may be exactly the reset the company needs.

By Verdad Gallardo | 2026-03-04 12:23:37


VIEW MORE
story-7
Engraved Rebellion: Inside Bundnerbike's Glam Rock II

Slideshow: A standard cruiser becomes an intricate metal canvas in the hands of a Swiss custom house known for pushing Harley-Davidson platforms far beyond their factory brief.

By Verdad Gallardo | 2026-02-24 18:19:44


VIEW MORE
story-8
10 Motorcycles You Should Never Buy

Slideshow: There is no shortage of great motorcycles to buy, but we would avoid these ten.

By Joe Kucinski | 2026-02-19 14:50:51


VIEW MORE
story-9
10 Things Harley-Davidson Needs to Fix in 2026

Slideshow: Harley-Davidson's challenges aren't abstract; they show up in dropping shipments, shrinking dealer traffic, and strategic decisions that aren't yet translating into growth.

By Verdad Gallardo | 2026-01-13 18:33:17


VIEW MORE