87 VF500F Overheating

Don't know much about the 500's yet, only just bought an 84 tonight and an 84 about a month ago. My daily rider is a 1984 V65 Sabre, so I'm "familiar" with some of the V4 quirks.

The 84 that I just bought a few hours ago seems to overheat quickly, about 10 minutes or so. The temp gauge goes to HOT. Now, I know some of the bigger V4's have had issues with sending units and fan switches in the past, but am wondering if the small V4's have some of the very same inherant problems.

I'm sure there are previous posts regarding this, but have only just now found the site so I thought I'd shoot a message and get some ideas before I start diagnosing the problems tomorrow. Someone point me in a direction please...

Thanks

Wayne
Austin, TX

84 V65 Sabre
84 VF500F basket case
87 FV500F over heater...for now

 

Have you started w/ the simple checks? Flush the radiator and make sure the auxilary fan comes on?

 

I've barely just unloaded the bike out of the truck after picking it up. Gave her a spin around the neighborhood and noticed the temp gauge...so no, I haven't given her a "once over" yet, that will happen tomorrow morning bright and early. Just wondering what problem areas to look for before I spend all day tracing down something that everyone here already knows about.

I've read a few posts that say 3/4 on the temp gauge is normal for these things, much higher than I'd expect considering my V65 Sabre only runs about 1/3 around town.

Wayne
Austin, TX

 

3/4 is pretty normal. I would still flush and fill the radiator and check and make sure the fan kicks on when hot.

If it does, I imagine youre fine.

Strangely, after I adjusted my valves into spec - the bike ran much cooler.

 

An '87 VF 500 would be a rare bird indeed.

BEFORE riding did you check to see that it had any coolant at all, or did you just assume it did???

 

Check to make sure that the thermostat is kicking on the fan. I had the same problem once with one of my 500s and that is all it was - a simple fix. Also, what year is your 500? Honda only made them from 1984 to 1986.

 

Thanks for all the info y'all. Looks like I do indeed have a 1984, according to the title. The VIN plate that is supposed to be on the frame is missing. Is there another location where the VIN# might be found on these things?

Also, haven't seen or heard the fan operate yet. I've checked to be sure it's not locked up, but it hasn't come on. Will check fuses and such next.

Wayne

 

OK, checked fuses and coolant level. FUses good, level full. Checked for power at the blue wire to the fan...has battery voltage. Also has battery voltage to the other wire as well. SHouldn't that be the ground?

Wayne

 

Another update.....jumpered the fan switch at the radiator and BAM, the fan turns on. Keeps the bike cooler, but still goes fully to HOT after a few minutes of riding.

Might try new coolant to see if that helps, there's only water in the system now. Previous owner didn't take very good care of this thing....

Wayne

 

stuck-closed thermostat ??

 

You could just remove the thermostat and run w/out it to find out, correct?

 

That'd work....


But actually...... the systerm needs the restriction of the thermostat to control the circulation so that optimum heat transfer happens in the radiator.

 

I was thinking the same thing, and I'm headed out to the garage to make that happen right now......

Wayne

 

Removed the t-stat, flushed the system. Added 50/50 coolant. Slowed the everheating down a bit, but will still go all the way HOT in about 15 minutes of riding.

With the radiator hose on the left side removed (the one that goes to the water pump) I started the engine and expected flow from the water pump side. Didn't get any.

What drives the water pump?

Wayne

 

looks like it's time to change the pump...............Babbitts Sports Center | Arctic Cat OEM Parts | Can-Am (Bombardier) OEM Parts | Honda OEM Parts | Kawasaki OEM Parts | Polaris OEM Parts | Sea-Doo OEM Parts | Ski-Doo OEM Parts | Suzuki OEM Parts | Yamaha OEM Parts
there are cheaper places to get it . just to show the view.

 

Oddly enought I thought the same thing. Found a repair order from about a year ago in a pile of stuff the previous owner gave me that showed the pump, thermostat, and coolant being changed...along with some "stop leak" being added. Got me to thinking about radiator flow, so I just pulled the radiator. Not clogged, but I can see alot of calcium (white, chalky) deposits at the end of the tubes. I'm suspecting that I've got some clogged tubes.

Fortunately I've got that basket case sitting in my shop. I pulled the water pump off of it a few hours ago but discovered the "new" one on the bike at my house. Now I'll have to get up early tomorrow and go scavenge the one off of the basket case and HOPE it's not clogged up. Supposed to be great riding weather around here tomorrow, and I wanna ride the baby Ceptor for more than 15 minutes at a time!

Wayne

 

Another UPDATE....Since I've got another 84 that's in pieces at my shop I decided to swap radiators. STILL gets hot.

New water pump that works, removed the thermostat, swapped radiators, flushed radiators, jumpered fan so that it stays on all the time. STILL goes all the way to HOT in about 15 minutes.

I grounded the wire for the gauge and the gauge climped to hot. I'm wondering if maybe I have a bad sending unit and/or air in the system.

What's the proper way to bleed the air from the cooling system?

Wayne

 

try switching the senders; your gauge is OK.

bleed air by running it with rad cap off for about 1 minute, then shut off and top up.

You should run a pressure test on the cooling system and rad cap.

One possible cause of that sort of overheating could be a bad head gasket..........

 

Bad head gasket might be why the previous owner allowed some stop leak to be added to the coolant when the water pump was done a year ago. I haven't swapped out the senders yet, probably tomorrow. Seems to run fine though, even when the temp gets to the far right of the gauge.

I just came back for a ride to allow it to heat up so that I could check for an external leak of some sort. None found. System is pressuring up nicely, hoses were nice and "hard" when the gauge was at 3/4.

Wayne

 

Put your hand at the end of the exhaust pipe and rev the engine.

Any slime shooting out? Even just tiny tiny drops?