Foam in Oil

3 replies to this topic
  • Greg_T_M

Posted October 12, 2010 - 01:57 PM


Finished putting my engine back together after some work, fired it up and let it idle for a few minutes. Dumped the oil and it was all foamy. Let the oil sit for about an hour and it cleared up. Put new oil in and let it run for a few minutes, blipping the throttle, dumped the oil and same thing. Cream colored foamy oil. The only thing that I could think of was something wrong with the head gasket, so I tore it back down again. Found one shiney spot on the gasket but really nothing out of the ordinary. Have a new gasket kit on the way and will try again.

Would like some clarification on the assembly procedure in the book. The best that I can understand it, they want the head bolts torqued to 22 ft/lbs, removed, regreased then torqued to 14 ft/lbs + 180 degrees. In order to get the head bolts out, the head must be pulled away from the cylinder and angled a bit for a couple of the bolts to clear the frame. This seems wierd to me and seems to put the head gasket at risk of damage by not returning to the exact same place.

Am I misunderstanding the directions or does it sound like something else may have gone wrong? Would like to get this figured out before the new parts get here.

Any help is appreciated.

Edited by Greg_T_M, October 12, 2010 - 03:46 PM.

  • grayracer513

Posted October 12, 2010 - 02:14 PM


You understand the process correctly, but you've also correctly identified a problem that arises when reinstalling the head on an '06-'09 model in the frame (don't know about the '10+ yet). Because of this, for those doing this job with the engine in the bike I recommend NOT removing the bolts in between the two tightening steps to re-lube them. If you use a good anti-seize lube, it won't be needed. Don't slop the stuff all over everything, just coat the threads.

As far as the foam in the oil, if the foam was due to coolant, that coolant will settle out and sink to the bottom of the oil. It may take a while, but it's a good check. What brand/type of oil?

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • Greg_T_M

Posted October 12, 2010 - 02:49 PM


Gray, thanks for the quick reply.

I'm using Castrol Actevo 20w-50 synthetic blend. I saved about a half pint to send in for oil analysis and within two hours all of the foam was gone and no evidence of coolant. This was on the 3rd change and after taking the bike out for a little spin to get fresh oil through the clutch plates. I also topped off the radiator and did not appear to lose any coolant. I'll put it back together, and not pull the bolts out for re-greasing.

If it continues to foam up after the new head gasket, I'll pull another sample and send it in for testing.

A couple more questions: What do you use for anti-seize lube, and who do you use for oil analysis. We use Signum for testing our hydraulic oil, but not sure about their motor oil testing.

Thanks again.

  • grayracer513

Posted October 12, 2010 - 03:11 PM


Permatex anti-seize, and Blackstone Labs.

Some oils foam far too readily, and because the return pump in a dry sump system runs faster than the feed pump by design, air is constantly in the return line. This aggravates any excess foaming tendency in the oil. Once you establish that there is no contamination issue, you might want to look into a new brand.

Related Content


Yamaha YZ450F 2017 by Chris.GVS

Yamaha YZ450F 2017
  • * * * * *
  • 1 review
  • Last review by Tommyk_55
  • On Yesterday, 06:20 PM

Should I buy this bike? help....... by Numsa Hul

Dirt Bike   General Dirt Bike Forums   What bike should I buy?
  • * * * * *
  • 10 replies

Michigan Motocross Tires by 288yz450

Dirt Bike   Dirt Bike Regional Discussion   North
  • 1 reply

Is it worth it? (Cam and High compression piston) by macgi77

Dirt Bike   Make / Model Specific   Honda   CRF 150/230 F/L
  • Hot  36 replies

Megabomb Fitment by 288yz450

Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • 1 reply

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.