85 vmax getting hot ?

[JEAN PIERRE EPSTEIN]

85 vmax fan kicks on at just below black dot but then never turns off and temp settles at 3/4 mark on gauge on motorway with fan still running but if i get in slow traffic it creeps up to just below the red and would probably keep going until i get moving again it is not the fan switch , headgasket, water pump , or blocked rad even the thermostat opened in boiling water but i think it must be the stat ? why is the fan despite running all the time once on not bringing the temp down ? any ideas john

 

[02GF74]

Is there an aftermarket radiator cover fitted to the front?
an example shown below.


When wad the last time the coolant (water and anti-freeze) replaced and was the system flushed with water?

 

[JEAN PIERRE EPSTEIN]

no stock cover. i have owned this bike since 1987 and even in california it used to run cooler i have come to the conclusion it must be the t,stat it boils down to the fan is continuously running yet not bringing temp down enough to kick off ?

 

[JEAN PIERRE EPSTEIN]

thanks for your response i need all the ideas i can get.

 

[02GF74]

OK. So could be thermostat, this can be tested by placing in a saucepan of water on a stove. It should open around 90 C. It would be easy and cheap to replace it.

It could be restrictions in the radiator channels due to hard water (I always use deionised water in any cooling system). There are flushing products for this.

It could be water pump inefficiency, for example impeller blades broken or bearings partially seized.

There is a valve at the front bottom part of the engine, is it set in the correct position (a black plastic hexagonal cap).

I'm tempted to throw in headgasket problem but that would usually result in coolant loss.

 

[JEAN PIERRE EPSTEIN]

Despite having tested the stat i have a feeling its the cause i have flushed the rad and it seems fine ? i will strip it all out tomorrow & see if i can find the problem. i have actually rebuilt this motor twice since 87 the last time installing a pcw racing 1428cc kit i wonder if that could cause it to run hotter ? i cannot think of any reason why ? what position does your gauge show if you are on the motorway on a hot day like today ?

 

[JEAN PIERRE EPSTEIN]

do you use just deionised water in your system ? i forgot to mention the motor was completely rebuilt and increased to 1428cc last year. thanks jp

 

[02GF74]

NO!!! I use de-ionised water instead of tap water - to ensure there are no dissolved minerals in it mixed with the recommended anti-freeze.

As an aside, I looked into this a while back and for optimum heat transfer the water/anti-freeze mix has to be in a given range, in other words you cannot use 100% water or 100% antifreeze.

re. engine rebuild - that is nearly 20% larger. Unless you modified the engine or have managed to rewrite the laws of physics, the efficiency of the engine would be unchanged, in other words I would expect it to generate 20% more waste heat.

I do not know if the stock radiator, bearing in mind this one is 30+ years old so could be crudded up inside, can handle that?

The gauges are not accurate so should be used as an indicator - when stationary, the needle will rise, the fan kicks in and it should turn off after a while with the needle dropping a bit.

An easy thing to try is to add water wetter, an example below:
the claims are:

• improves heat transfer and reduces cylinder head temperature
• Compatible with new or used antifreeze (including DEX-COOL® and long-life versions) to improve the heat transfer of ethylene and propylene glycol systems

Note I tried a similar product in a car engine and am not convinced it made any difference but other people swear by it.

I would recommend you have a peak inside the radiator to see if there are deposits in the channels - this may require it to be removed but a $5 endoscope the connects to a phone would make life easier.

Incidentally for the price of 2 thermostats, you can get an after marker all alloy radiator, again example posted below.
( This radiator is heavy duty designed, cooling capacity is increased ,really well packed, exceeds OEM spec. )

One thing to try is to remove the thermostat and run the engine when stationary on a warm day. If the fan never turns off, then the system is not capable of cooling the engine so we're looking at step 5 and beyond.

So my recommendations are in the following order (and in cost!)
1. check the valve position
2. flush out the system - see example product
3. refill with de-ionised water and recommended anti-freeze
4. replace thermostat
5. remove water pump to check it out
6. look at fitting upgraded radiator

 

[Fire-medic]

You increased the displacement by 20%, yes, of-course it's gonna run-hotter. Use some aids like water wetter (I've read posts saying use it not with antifreeze, but distilled or ionized water) or some other similar product.

02GF74 gave some good advice, I was writing when he posted.

 

[JEAN PIERRE EPSTEIN]

THANKS FOR ALL YOUR POINTERS IM A FIRM BELIEVER THAT DESPITE HOW MUCH YOU THINK YOU KNOW 2 MINDS ARE ALWAYS BETTER THAN ONE. I WILL COMPLETELY STRIP OUT THE COOLING SYSTEM TOMORROW & SEE HOW IT GOES. I WILL KEEP YOU POSTED & THANKS AGAIN. JP

 

[02GF74]

from manual; thermostat
opening temp: 80-84C
fully open: 85C
valve lift: 8mm (minimum) - I would test this by inserting an 8mm drill into the gap or a trip of metal - don't take it out of the hot water as it will start to cool and therefore close - if it closes with the drill bit in place, damage may occur.

From the manual I notice it should be possible to fit a larger diameter fan but looking at the bike, I ma not sure sure there is space.

Once you have checked original cooling system is in tip top condition and problem has not gone away, then something like this is the way to go (it would be useful to get input from those who have tuned engines!)
Upgraded 2 Row Aluminium Radiator For YAMAHA V-MAX/VMAX VMX1200 VMX12 1985-2007 | eBay

£ 69 ... which I think is very cheap.

This Aluminum Radiator is at least 35%-45% more efficient than stock ones. Most importantly, it has a much higher capacity for coolant than stock ones, which means that your cooling system will be more efficient and will be more resistant to temperature surges in racing applications.​

 

[02GF74]

A couple more thoughts.
check the fan and motor:
- are fan blades unbroken and attached to the motor?
- is motor spinning in correct direction; it should pull air through the radiator (I don't recall what the connector to it is like but would expect it can only be fitted one way)
- check the contacts in the connector are not corroded

 

[user 16790]

probably a crazy idea but could the wires to the fan be crossed causing it to spin the wrong way

 

[JEAN PIERRE EPSTEIN]

Thanks guys I will take all your thoughts on board and go through the cooling system over the next 2 days I have already ordered an aluminium rad. one thing I will say in over 25 years of owning a VMAX and friends who have owned them I have never seen a water pump have any fault other than the occasional leak I was speaking with john at PCW racing New York yesterday and he said that the gen 1 water pump is pretty much bullet proof but you never know. thanks jp

 

[02GF74]

..... well there is always a first time for everything but no harm checking the full cooling system is functioning correctly.

re: alloy rad (BTW which one have your ordered?) - these are sold in raw metal finish but matt black is the best colour for radiating heat.

Radiators, despite the name, lose heat via convection (air flowing through them) so a thin layer of paint should make that less efficient due to its insulating properties but I doubt it matters for our purposes that matters.

 

[Screwloose]

Radiators, despite the name, lose heat via convection (air flowing through them) so a thin layer of paint should make that less efficient due to its insulating properties but I doubt it matters for our purposes that matters.

Absolutely.
A quick story: A few years ago a friend bought a motorhome and during a trip to Spain he thought it a good idea to paint the tarnished copper pipes that run to the exterior of the motorhome, they were the copper pipes from the fridge. The fridge stopped cooling and we scraped the new paint back off. The fridge started cooling again.

I’ve never looked into paints, but there must be some out there that are poor conductors of heat, and want to insulate. A bit of research is then needed before using paint on a radiator.

 

[apsolus]

ive heard the car guys will drill a hole in the base of the thermostat so its always flowing a little bit. might help with flow, if flow is your problem. they also make restricter plates that replace the thermostat all together with a open hole. ive seen that with cars too. even my bone stock vmax will get hot if it just sits there running. some bikes just do that in general some bikers will start lane splitting or pull over to avoid overheating in traffic. with engine mods id be happy it cools while in motion. maybe an aftermarket fan switch would help so you can turn it on sooner in traffic so the bike doesnt get the chance to run hot

 

[Screwloose]

ive heard the car guys will drill a hole in the base of the thermostat so its always flowing a little bit. might help with flow, if flow is your problem. they also make restricter plates that replace the thermostat all together with a open hole. ive seen that with cars too. even my bone stock vmax will get hot if it just sits there running. some bikes just do that in general some bikers will start lane splitting or pull over to avoid overheating in traffic. with engine mods id be happy it cools while in motion. maybe an aftermarket fan switch would help so you can turn it on sooner in traffic so the bike doesnt get the chance to run hot

I’ve done allot more work on cars than bikes and what you say is true, it’s an old trick that when your car is overheating and especially if your away from home, punch a couple of holes in the thermostat, or remove it completely if possible. You lose a bit if fuel consumption when you do this as your engine is not at ideal operating temp, but it saves your life if your many miles away from help.
When my Vmax was overheating I ran it for a couple of weeks with a punched out old thermostat, again not the best thing to do long term, but it gives you time to reflect on the cause of the overheating, as during investigating your constantly panicking when the temp rises. Eventually when I sorted the problems I discovered there are 2 thermostats that fit the vmax gen 1, that also control 2 different temps, cant remember the suppliers but they are out there.

 

[JEAN PIERRE EPSTEIN]

DO NOT BUY THE ALLOY WORKS UPGRADED VMAX RADIATOR ON EBAY ITS £69.00 AND A TOTAL PIECE OF **** FROM THE GROMMETTS TO THE FAN MOUNT NOTHING ******* FITS THEN WHEN YOU HAVE SPENT THE WHOLE DAY MODIFYING IT YOU REALIZE IT OBSTRUCTS THE ******* STEERING A TOTAL PIECE OF ****.

 

[Fire-medic]

I discovered there are 2 thermostats that fit the vmax gen 1, that also control 2 different temps, cant remember the suppliers but they are out there.

That info is on this website & all it takes is a bit of a search. Same for the temperature sending switch.

(77) Noob overheating/ popping question 2003 | Yamaha Star V-Max VMAX Motorcycle Discussion Forum (vmaxforum.net)