White smoke from engine when hot....

[MattyFJ]

Hey Guys

I'm about to delve into this problem I've had for a while, but just wanted to make sure I'm looking for the right thing.  On a mild/cool day, she runs great, no issues, but if its really hot, or I'm in stop and go traffic (which is a lot here...) I'll have some white smoke coming up from under the tank (out of the "grilles" on either side, just below the seat.  Its an '84).  At first I thought this could be a fuel leak, but it didn't make sense the longer I thought about it since it would be leaking whether cold OR hot.

So my next thought came to oil.. but from where?  Its a bit of an odd place to get leaking oil, unless there's a crankcase breather that's come loose or is just not there...

Like I said I will be tearing into it to get it fixed.. its a little disconcerting to ride a smoking bike.. when the smoke isn't coming out the exhaust... and sure as hell can't be water

Am I on the right track thinking its oil from somewhere?

Thanks!

[rktmanfj]

Hey Guys

I'm about to delve into this problem I've had for a while, but just wanted to make sure I'm looking for the right thing.  On a mild/cool day, she runs great, no issues, but if its really hot, or I'm in stop and go traffic (which is a lot here...) I'll have some white smoke coming up from under the tank (out of the "grilles" on either side, just below the seat.  Its an '84).  At first I thought this could be a fuel leak, but it didn't make sense the longer I thought about it since it would be leaking whether cold OR hot.

So my next thought came to oil.. but from where?  Its a bit of an odd place to get leaking oil, unless there's a crankcase breather that's come loose or is just not there...

Like I said I will be tearing into it to get it fixed.. its a little disconcerting to ride a smoking bike.. when the smoke isn't coming out the exhaust... and sure as hell can't be water

Am I on the right track thinking its oil from somewhere?

Thanks!

More than likely, it's burning off leaked oil from the cam cover gasket/grommets.

[MattyFJ]

Could definately be.. which itself isn't a huge deal since I have to get the valves adjusted anyways.  Simple matter of a new gasket at that point.

[rktmanfj]

Could definately be.. which itself isn't a huge deal since I have to get the valves adjusted anyways.  Simple matter of a new gasket at that point.

If the gasket isn't hardened, it's probably okay.

The grommets harden up, shrink, and crack, letting tension off the gasket, and leaking oil everywhere.

But, if you're going there anyway, might as well go ahead and do it, too.

[FjLee]

I'll have some white smoke coming up from under the tank (out of the "grilles" on either side, just below the seat.  Its an '84). 
Thanks!

Does it do this all the time, or just after you've lubed the chain?

My 84 will smoke a bit after I've lubed the chain.  I can smell it too...........

FjLee         84 FJ1100          Denver CO

[FJmonkey]

Sounds like my '86 when I got it, the valve cover grommets were leaking/weeping oil and it drips down where the exhaust heat cooks it off.

[PaulG]

I had this once stuck in +30 degC stop & go (mostly stop) traffic for abot an hour.  Turned out my choke cable melted from the heat off the cam cover.  If your choke cable hasn't seized, then that's one source eliminated.

[aviationfred]

 I never had actual smoke billowing out anywhere, but I had similar symptoms before I rebuilt the engine.

I have a theory to offer. The smoke could be coming from the engine breather. Low cylinder compression causing the crankcase to pressurize. I have UNI pod filters and a crankcase vent filter. My thoughts are...... Knowing that my cylinder compression numbers were south of 120psi, that there could be some blow-by of the pistons and the crankcase was getting slightly pressurized.  

If I pulled my seat and a side cover off while the engine was still hot..... I would get a very strong oil smell and wisps of smoke coming from the breather filter. I was constantly cleaning the filter as it would be drenched in engine oil.

500 miles in the rebuilt engine and the breather filter is still a nice rosy pink color and I get no oil smell.

Fred

[4everFJ]

It sound like "normal" overheating.

These big aircooled engines doesn't like stop-n-go traffic in high temperatures. When the engine overheats, lots of stuff starts to smoke (dirt, oil, plastic, etc..).

Make sure that EVERYTHING is adjusted/maintained correct and err a little on the rich side with your fuel mixture. You can't cure the problem (aircooled engines needs airflow to cool down), but you can minimize it with a well maintained engine.

An alternative could be to fit a bigger oil-cooler, but in stop-n-go traffic it doesn't have that much effect (even big oil-coolers needs airflow to cool the oil).

I had the same issue when I bought my FJ. But, after doing a full maintenance (adjust valves, clean and adjust carbs, etc..), the problem is nearly gone and it takes a lot more before it starts to overheat.

[MattyFJ]

Thanks for the help guys, I can definately say I now know what it ISN'T.

Cam cover seal & grommets were fine, no oil in the airbox.. the damn leak is coming from the FRONT of the engine and when it hits the exhaust it wafts up everywhere.. was finally able to catch it after heating her up and letting it sit running for a bit.  It seems like its either coming from the oil drain plug (unlikely since I torque to spec and put a new crush washer on each time), the oil cooler fittings, or seepage from around the oil pan itself.  Oil pan doesn't seem likely, but there does seem to be an inordinate amount of grime near the oil cooler fittings.  So, time to drop the exhaust and take a look at those bolts, and seals.  My hex socket bits aren't long enough to clear the supertrapp headers

After heating up and left to cool down, it does seem to "mark its territory" with a few drops... makes sense, oil gets warm, thins out, seeps out a tiny crack.  Cools off, oil too thick to seep, leak stops.  But the position under the bike doesn't give a clear idea to where its leaking since it drips off the headers, and on an angle due to the sidestand. 

[Bones]

Could be the oil galley plug on the front of the block too. It might've been tampered with once and could be loose, cracked, or the o ring broken.

[The General]

Treat the bike like yourself.....A good wash & dry, followed by puffs of baby powder on all the suspicious bits! Turn it on, then watch what happens....... preferably with a second person checking out your moves! 

[red]

Thanks for the help guys, I can definately say I now know what it ISN'T.
My hex socket bits aren't long enough to clear the supertrapp headers

MattyFJ,

Get a hex bit holder on the end of a ratchet extension shaft, which may extend your reach enough to do the job.  
Most socket sets will have a hex bit holder, lately.  A 1/4" drive ratchet wrench might be good enough for the work,
or use a 3/8" drive ratchet, maybe with a reducer to a 1/4" drive.

You can use a common 1/4" socket (or whatever size fits your apex bits) as a hex bit holder; just hold a thin rubber band
over the hole and push the hex bit down into place in the socket.

Cheers,
Red

[FJ_Hooligan]

The O-rings on a few of my oil galley plugs were somewhat squared off and lacking in sealing ability.  One of these is on the front of the motor.  A few new ones from Randy fixed me right up.

[ribbert]

.....So, time to drop the exhaust and take a look at those bolts, and seals. 

I'd try to identify the source of the oil leak before you pull it apart if possible, it will be easier to find if you can run the engine and get it hot.
Oil leaks are not always easy to identify with a visual inspection of dismantled parts.

Noel