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coolant leaks on my 1992 VFR750F


huami

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Hi!

I'm seeing coolant level going down and a wet patch under the bike constantly. This has been for 2 years at least and finally I decided to do something about it.

Last year I replaced o-ring #7, the big one on the water pump cover but it didn't help much. Recently I noticed the o-ring #21 on the water pump itself was not good (flat and old) so I will replace that. I wonder if the oil seal in the water pump is also replaceable as I don't see it on the list of parts and the water pump itself is not available anymore (and a bit costly even if it was available):

https://www.fowlersparts.co.uk/parts/5053486/vfr750fn-1992-it/water-pump-vfr750flfmfnfp

The seal:

20230222_081416.thumb.jpg.7f7463861b1e5dfee3fe02134343ad0a.jpg

 

Now I'm worried that I have an oil leak actually and water mixes with the oil. The o-ring I'm going to replace n the water pump is causing that leak and it looks like oil:

 

20230218_104049.thumb.jpg.b82ead9c1ec488514b02e513c2d3296c.jpg

 

Sings of water in the oil:

20230218_135439.thumb.jpg.7b0e67313348b0c140b2326e3a592201.jpg

 

Is that really bad? Hope that's not head gasket.

 

Any other seals I could replace? The service manual tells about oil pump mechanical seal? Where do I find that?

 

Any suggestions more than welcome.

 

Thanks!

 

 

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I suppose the best thing to do is to replace the O-ring and see what happens then. These engines are not prone to head gasket failures, they're some of the most solid engines that Honda ever made really. It's possible that oil residue is being diluted by leaking coolant and is making it look worse than it is. 

 

Any idea if your oil level is dropping? That'd be another clue too.

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I think my engine can be reaching 100k miles (hard to say as it was originally from Swiss, then imported to Poland, then moved to UK). Even the best engines have their life limit, but hopefully it is not the case 😅. The o-ring is now replaced and at least the leak outside should be gone. I just need to do some more work (noises from the clutch) and it should be back on the road.

 

The oil level was never dropping and once I think I noticed it went up, but it wasn't so obvious. I was not riding the bike too much in recent years though.

 

I'm still looking for that oil pump mechanical seal and once I find it I'm going to replace it too. I'm also doing on the clutch now, will be putting a new/old clutch set. Any replaceable oil seals there I should look at while I'm doing it?

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  • Member Contributer

The only places I can think of coolant getting in the oil would be, Head gaskets-unlikely, and water pump-probable. There was someone that was rebuilding the pumps that I think just sold the business. I'm sure someone will chime in with the info on that.

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  • Member Contributer
On 2/22/2023 at 7:44 PM, huami said:

Hi!

I'm seeing coolant level going down and a wet patch under the bike constantly. This has been for 2 years at least and finally I decided to do something about it.

Last year I replaced o-ring #7, the big one on the water pump cover but it didn't help much. Recently I noticed the o-ring #21 on the water pump itself was not good (flat and old) so I will replace that. I wonder if the oil seal in the water pump is also replaceable as I don't see it on the list of parts and the water pump itself is not available anymore (and a bit costly even if it was available):

https://www.fowlersparts.co.uk/parts/5053486/vfr750fn-1992-it/water-pump-vfr750flfmfnfp

The seal:

20230222_081416.thumb.jpg.7f7463861b1e5dfee3fe02134343ad0a.jpg

 

Now I'm worried that I have an oil leak actually and water mixes with the oil. The o-ring I'm going to replace n the water pump is causing that leak and it looks like oil:

 

20230218_104049.thumb.jpg.b82ead9c1ec488514b02e513c2d3296c.jpg

 

Sings of water in the oil:

20230218_135439.thumb.jpg.7b0e67313348b0c140b2326e3a592201.jpg

 

Is that really bad? Hope that's not head gasket.

 

Any other seals I could replace? The service manual tells about oil pump mechanical seal? Where do I find that?

 

Any suggestions more than welcome.

 

Thanks!

 

 

I had a similar issue with my 2014. I noticed coolant on the ground under the bike and in the fairing belly. It was coming from the pump weep hole and I determined that the mechanical seal had failed, I think because the bike shop who did the first valve clearance check may have replaced the coolant with one with silicates. The mechanical seal is in the bowels of the water pump and not accessible by your average home mechanic. I ended up replacing the pump and all was sorted. Maybe a newer model pump might fit your bike, if you can’t source an original or find a pump repair specialist.

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  • 3 weeks later...
  • Member Contributer

It's good there is none on the ground, but what will kill the bike is the coolant in the oil. You have to make sure it is not getting in there.

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