2017 Massimo 700-5 Coolant system trouble

[TimMassimo]

Hello. I have a 2017 Massimo 700-5. I have recently had the head gasket replaced with the head and base machines, all gaskets, valve seals, piston rings and a coolant flush. I drove it for about a total of two hours at different times and days and now the coolant is not reaching the head when it is running. I have tried to bleed it by jacking up the front end using the top screw in the water pump screw and get all the air out. After I run it for a few minutes the coolant get stuck in the radiator and it won’t circulate back to the head as it should.  Has anyone run into this? I’m not sure if there’s air in the system or the water pump does not work?  

[T-boss 410]

Well, is the radiator getting hot? Feel the hoses at the radiator, and if they are hot, the water pump is pushing coolant. I see you have a new head gasket, etc., but it almost sounds like a blown head gasket which is causing enough pressure to keep the coolant from reaching the head. 

Also, sometimes it takes several attempts to get all the air out of the system. It can be a royal pain to deal with. Just don't let it overheat! These engines don't respond well to an overheating issue. I'm sure a member here (Joe Breaux) can shed some light on your problem. 

[TimMassimo]

T-Boss 410, thank you for replying.  The radiator is cold at all times.  When I got it home it ran great and the coolant was cycling properly- then just stopped cycling randomly.  I was told the coolant system may need to “burp” although not sure how that works short of the normal bleeding process. Thanks again!

[T-boss 410]

Better check your thermostat, too. It may not be opening, which would not allow the coolant to circulate and run through the radiator. 

[TimMassimo]

I don’t believe there is a thermostat as the mechanic did not put one in- couldn’t find a match to fit. I will try to run it at idle and add coolant as it burps out and hope for the best.  The next step is to replace the water pump if that doesn’t work.

Thank you for help!

[kenfain]

On 11/30/2020 at 5:50 PM, TimMassimo said:

I don’t believe there is a thermostat as the mechanic did not put one in- couldn’t find a match to fit. I will try to run it at idle and add coolant as it burps out and hope for the best.  The next step is to replace the water pump if that doesn’t work.

Thank you for help!

Looking at a water pump when it's in the hand is usually pretty easy to diagnose, because it'll turn roughly, with grinding, or be loose with sloppiness in the shaft. Lots of rust, leaking at the shaft, etc. Any one of these fairly obvious problems means a bad pump. 

Maybe just pulling the belt off and spin it freehand, and do a good visual check too. Or worst case, you have to pull it off to check it. If it's determined to be good, you're only out the price of gaskets. So I'd check it out before I just replaced it. 

I've heard of serpentine belts, that could be routed backwards over the water pump. Making the thing spin backwards. I'd consider that a severe longshot. 

Personally I'd suspect air in it, except for the fact that it was working good before. That seems a bit strange. But what's not uncommon is having to purge the air a couple times, or more on some vehicles. As you said, just keep topping it off for a few short drive cycles. See what happens. 

[Joe Breaux]

On mine it has a vent screw at  the pump and at the hose outlet on the head.. You must bleed out the air repeatedly from both as you add coolant with caps off .. if there is any air, the water will not flow .. you can drive it til the end of time and that air wont move by itself.  You have to get it out ...Overheating is a major issue with Massimo ... 

[TimMassimo]

17 hours ago, kenfain said:

Looking at a water pump when it's in the hand is usually pretty easy to diagnose, because it'll turn roughly, with grinding, or be loose with sloppiness in the shaft. Lots of rust, leaking at the shaft, etc. Any one of these fairly obvious problems means a bad pump. 

Maybe just pulling the belt off and spin it freehand, and do a good visual check too. Or worst case, you have to pull it off to check it. If it's determined to be good, you're only out the price of gaskets. So I'd check it out before I just replaced it. 

I've heard of serpentine belts, that could be routed backwards over the water pump. Making the thing spin backwards. I'd consider that a severe longshot. 

Personally I'd suspect air in it, except for the fact that it was working good before. That seems a bit strange. But what's not uncommon is having to purge the air a couple times, or more on some vehicles. As you said, just keep topping it off for a few short drive cycles. See what happens. 

Thank you for the insight. I haven’t taken the cover off the water pump yet but now I’ll know what to look for. It is strange that it was fine for the first run of about an hour and now not so much.  Generally I don’t run it for more than 30 minutes or so since I’ve had it back. Thanks!!

[TimMassimo]

4 hours ago, Joe Breaux said:

On mine it has a vent screw at  the pump and at the hose outlet on the head.. You must bleed out the air repeatedly from both as you add coolant with caps off .. if there is any air, the water will not flow .. you can drive it til the end of time and that air wont move by itself.  You have to get it out ...Overheating is a major issue with Massimo ... 

I just found the screw at the pump but my mechanic didn’t know there was one there, only the top screw. It must be air bound. Thank you!!

[Joe Breaux]

I am assuming the bleeding at second vent screw I suggested got all the air out and resolved your no coolant flow?  It would be helpful if members would put up a final post to say what happened... could help the next guy 

[TimMassimo]

Hi Joe.  The coolant would make it to both sides of the motor although once I cranked it up the pressure was to much and forced the water out of the coolant reservoir.  We are assuming it’s a head gasket issue that will need to be replaced. 
 

Thank you for your trouble shooting assistance! 

[Joe Breaux]

if its blowing out the reservoir, ITS A HEAD GASKET LEAK for sure .. these things are plagued with head gasket failures... try to use a YAMAHA gasket this time 

[rsheve]

Does anyone have a part number or can direct me to the Yamaha head gasket the will work for my 2015 EFI Massimo 500?

[Joe Breaux]

I dont have the part number.. My mechanic did the work..  but The HISUN 500 is a clone of the earlier Yamaha Rhino engine.. almost identical in every way.. he said Yamaha gasket was better quality ...its working great now.   Engine rebuilders say you can swap a Rhino engine into Massimo and it will all bolt up        

[TimMassimo]

14 hours ago, Joe Breaux said:

I dont have the part number.. My mechanic did the work..  but The HISUN 500 is a clone of the earlier Yamaha Rhino engine.. almost identical in every way.. he said Yamaha gasket was better quality ...its working great now.   Engine rebuilders say you can swap a Rhino engine into Massimo and it will all bolt up        

Thank you!

[TimMassimo]

On 2/13/2021 at 1:55 PM, Joe Breaux said:

if its blowing out the reservoir, ITS A HEAD GASKET LEAK for sure .. these things are plagued with head gasket failures... try to use a YAMAHA gasket this time 

Thank you. I will look for the Yamaha gasket. I’m thinking of using Gasket Cinch in addition as well.