2004 YZ450 Engine / Coolant issue

2 replies to this topic
  • Bill_R

Posted September 02, 2011 - 10:20 AM


Hi all

I am new to the forum, but based on what I see, this may be the place to get some advice on an issue I have.

I picked up a 2004 YZ450F that has been sitting for many years. I got it home and managed to get it started, but it was getting coolant in the oil. Most people advised that it was the seals in the water pump. So I had the complete water pump rebuilt (seals, bearing, shaft everything). The shaft had some pits in it from sitting in the coolant for many years. Got it running again, and it was running real bad, so I had the entire carb rebuild. Now it was running strong, but had a faint smell of burnt coolant. Just to be sure, I drained the oil to get it cleaned out, and there was coolant in the oil again. So now I had the head pulled and put a new head gasket in. Started it up again, and same deal. Coolant in oil and smells like it was burning some off.

So now the shop is thinking some or all the transfer seals on the lower casing may have dried and are leaking. Does anyone have any ideas on how to narrow this down? What else it could be?

Any advice would be appreciated.


Edited by Bill_R, September 02, 2011 - 10:34 AM.

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  • grayracer513

Posted September 02, 2011 - 01:56 PM


The water pump seals cannot be at fault.


  • Bill_R

Posted September 06, 2011 - 05:32 AM


Everything has been checked other than the lower gasket and crankcase seal. I am going to have the head and cylinder pulled this week to have them magnafluxed. If that all passes I will replace the rest of the gaskets / seals. I will post a reply if we are able to find the issue.



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