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Engine Overheats Within 5 Minutes Of Starting


crshovrd

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Hi y'all,

So I live in California and I know it can still be balmy this time of year but this bike is seriously hosed I think and I am looking for everyone's opinions. Also, I just purchased a new motor which will hopefully be here some time this week... anyone want to help with an engine swap and/or have any chain tools :)?

Current motor has 72k miles and was owned by a mechanic previously and he said he took care of it... it's a 94 and seen it's fair share of road rash... but it still pulls like an Ox.

So, first my fan switch wasn't working as the fan would never come on even though the gauge was reading high so I bypassed it and put in my own switch. That seemed to work for a bit but then the temp just kept climbing and climbing over half then eventually over H! This was over a period of months. Now the thing is pegged at H within the first 5 minutes of starting and sometimes i see white smoke from the exhaust... i know this is a tell-tale sign of head gasket failure and since i've been riding it like this for a bit... i figure the engine may not be salvagable, at least by me. So I bought a new motor for $340 shipped with a a 30 day gaurantee with about 29k on it from a 97.

Just for kicks, what could possibly be the issue with the current engine? Is the immediate rise in temp due to head-gasket failure? It has enough oil and coolant.

Also, anyone need a motor with a possible blown head-gasket?? :)

Thanks in advance!

BTW, I LOVE MY VFR!!! I owned a 92 before this one.

Also, seriously, if anyone in LA has a chain tool I could borrow that would be awesome!

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  • Member Contributer

I am not sure mine even warms up in 5 minutes, might be worth using one of the touchless thermometers to see if it is getting hot, might be a bad sender.

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  • Member Contributer

you have a 91 and live in southern cali... aka land of shake and bake..

remove the thermostat and cut the plunger off aka the spring loaded plunger . reinstall and never worry about over heating in traffic again. :wink:

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Hey thanks for all the input everyone!!! Good advice on the thermostat! I will give that a shot for sure. I did end up getting a new motor with about 1/4 the miles on it for $340 shipped... which now seems like overkill if it was just a thermo...

but i was seeing some white smoke which lead me to believe it was the head gasket..

I did think about getting a no-contact thermometer or pyrometer to actually check the enginer for temperature but haven't done that yet either.

all great suggestions!

I think at this point I will just swap the motor because that will be fun ;)

i'm hoping my old suzuki frame tools will fit this thing! otherwise time to make my own!

thanks again everyone and I will post back when the swap is over...

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  • 3 months later...

Hey everyone! So I took the radiator to a shop and they told me they couldn't powerflush it because the inlets are too small and they can't take apart an aluminium radiator... but i showed him the cap and with one touch he said it was bad because the rubber seal felt like plastic and was very hard.

I just called my local dealer and he said that the part (CAP) would cost $25 and is special order... this is a 1994 VFR 750... is it really required for me to use the HONDA specific cap or can i just go to an autoparts store and ask for a 16lb cap that fits?

What are the thoughts on these things?

also, I am going to take a hose to the radiator to see if i can flush some crap out...

Thanks!

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  • Member Contributer

The first thing that comes to mind is the thermostat. Regarding the cap, I always use genuine Honda parts on my bike. Always.

You may want to consider getting a new bike. Your bike is over 20 years old and you've got to ask yourself whether or not it's worth spending a lot of time and money on it.

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LOL... thermo is new.

I just did a motor swap... i love this bike and hate financing... so no new bike for me. And just cause it's 20 years old doesn't mean it sucks and isn't worth it... i mean.. i spent $950 for this bad boy...

anyway... so i guess i should just go for the honda cap... OK

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A number of people suggested a possible problem with the thermostat and you didn't mention anywhere that you subsequently replaced it.

I never said or even implied that your bike sucks. All I said is that it's over 20 years old and you may want to consider getting a new bike. With a bike that old, chances are you're gonna be having problems with it. In any event, I'm glad you're enjoying it and best of luck to you.

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  • Member Contributer

If you see *continuous* temps higher than 220ºF or below 180ºF then
trouble shooting is in order:

Continuous engine temps above 220ºF or 104ºC is also a problem and the proper
order of items to trouble shoot are:

1)Faulty radiator cap... system should hold 1.1 pressure ratio...
2)Insufficient coolant...
3)Passages blocked in the radiator, hose or water jacket...
4)Air in the system...
5)Thermostat stuck closed...
6)Faulty temp meter or thermo sensor...
7)Faulty fan...
8)Faulty fan switch...

Engine temps below 180ºF or 82ºC is an problem... it means that the
moisture produced during combustion is not getting hot enough to
evaporate out the pipe as steam... instead that moisture will migrate
to the oil and produce a milky white contamination...

Note normal by products of combustion is water... . Every gallon of gas
creates roughly 8 pounds of water vapor... we all have witnessed water
escaping out of tail pipes on cold mornings...

The sequence of events to trouble shoot are:

1)Faulty temp meter...
2)Thermostat stuck open...
3)Faulty fan switch... (stuck on)

Leaky Head Gasket Check...

You can visual inspect for a leaking head gasket by pulling the spark
plugs and peering down each hole... if the top of the piston is black
then no leak that cylinder... if the top of the piston is a bright
shiny aluminum then leak detected... because a leaky head gasket
allows coolant in and that produces steam under the heat of
combustion... the net effect is a super clean piston dome and no nasty
black...

On bike Thermostat Check

To check if the thermostat is opening start the engine at its lowest temp...

open the rad cap... observe at what temp the coolant begins to flow...

if the temp rises above 180F and the coolant does not flow then your

thermostat is suspect

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Rad caps from some Toyotas and Isuzus will work, as long as they carry the same pressure rating.

I've had one on my bike for years and years now, and working fine.

MotoMaster (Canadian Tire brand).

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