Welcome to Netrider ... Connecting Riders!

Interested in talking motorbikes with a terrific community of riders?
Signup (it's quick and free) to join the discussions and access the full suite of tools and information that Netrider has to offer.

Unusual Oil Trend GPX250

Discussion in 'Maintenance and Servicing' started by Operator, Aug 2, 2012.

  1. Okay, the story. I was given a repairable write-off '88 GPX250

    Full story is below. But I will jump to the problem and what I know:

    I have been trying to get the bike running after 4 years sitting idle. Carbs cleaned and fresh fuel, new fuel and vacuum lines and so forth. This question is about the current results I am getting:

    Oil colour started out milky. It is improving but not perfect after 5 flushes, 3 filters. Water level drops a little but doesn't seem to drop by any more than an inch in height from each fill (have not run the bike up to temp to get the coolant flowing fully yet). Oil level drops by 300ish mL after each fill but no sign of it on the ground or in the pipes/exhaust or carbies and each time I clean it there is less of this mysterious white smoke coming from around my engines exhaust ports. Other than that the bike responds to throttle very well, only needs half choke to start usually. And everything else is fine. I just can't get it to behave completely normally with regards to oil colour/level. As I said there is no sign of either a coolant or oil leak (internal or external). Is this unpredictable and non-uniform behaviour normal with a bike that has not been run for so long?

    Further explanation for those who may ask for details:

    Oil started out milky white, then deep vanilla, light vanilla, coffee brown and now caramel fudge coloured. I changed the oil out fresh after each 5-10 minutes and the filter was changed on the 1st, 3rd and fifth change (which is where i am at now I am asking). I knew the engine had been left adequate chance in the last 4 years to get condensation in it, side cover botls finger loose during intermittent attempts by the last owner to fix it. I have just swapped in the last of 3 filters I bought for the purpose of flushing it and am hesitant to waste any more oil before asking for ideas on if this is a good approach?

    Coolant level drops from full by about 1inch in height after any top up. This corresponds the the head height of my filler cap (with its overflow valve) height above the radiator itself (they are connected by about an 3inch long elbow joint that leaves the radiator horizontally and turns upwards to the cap. I cannot see any sign of coolant going anywhere, other than a few drips to the overflow when I start it once it is filled each time.

    Oil level seems to always go down about 300ml after a fill, with each run but there is no blue or white smoke coming out my exhaust since the first run (which may have been dust and crud from over the years. Didn't smell oily, foul stench like burning hair and dust but not oily)

    A lot of smoke came off the (largely dirt covered and part rusted) exhaust pipes, the cans are still pretty good though. This seems to have stopped with polishing them (the pipes) to a shiny steel and re-painting them with exhaust paint.

    Some white smoke (not oily though) comes from near the exhaust ports on the engine when it warms up after 5-10 minutes of running. As near as I can tell because with the mounting brackets for the exhaust I was a bit lazy cleaning them thoroughly as I was working on the pipes themselves.

    Most of the parts damaged had been pre-replaced, e.g. forks, steering stem and replacement frame. The guy who owned the bike (a friend of a friend, I got the bike and story 3rd hand) rides very hard and when I got the bike it hadn't been started for 3-4 years due to him being to lazy to replace the above parts and he'd whilst trying to tinker with it himself dumped the clutch and broken a few of the friction plates.

    4 years on, having had the clutch cover left with the bolts only finger tight for the time, I get the bike. I started by cleaning the entire thing, repainted the frame and made sure it was structural sound. Took the clutch cover off, replaced the basket and every clutch part to be 100% sure I had not missed any damaged parts. All the gears and other parts are still good. Clutch sacrificed itself to save them :]

    Can anyone suggest if there is a problem I am missing or keep flushing the oil till it stays clean?... I can't see any sign of where it would be getting any more moisture from to go white and as said, it has been improving each time. With each change being run for 2-10 minutes (whenever the oil took a very obvious colour change and seemed to stop changing colour.
  2. Ok someone stop me if this does not sound possible but:

    Coolant or water in the oil would make the oil change to that colour. I vote for a possible failed seal in the water pump allowing it to leak in?
  3. Almost certainly water in oil, if it was a car engine either water pump or head gasket, cracked head etc. sounds like an engine pull down to me. Look to some further input from some of the experienced bike folks on the forum, it will come.
  4. Well if it was a car it would be likely a head gasket but i can
    Sense ur smart enough to know tbat
    There is old school test call leak test
    Air pressure - not too much into plug hole
    Look fof bubbles in coolant.

    Note condensation water will evaporate n self fix so dont
    Get caught thinking its just that
    But it needs a run to evap so catch 22
  5. Yea, I thought leaking seals a mix of coolant and oil. But I have watch the coolant level very carefully and it always is at the same level other than that mystery level that disapears. Which I think but haven't verified is going out the overflow. I have a car that recently had a similar issue, so I thought head gasket or other similar issues.

    Thanks for the thoughts though, will look at doing a pressure test on the cooling system.
  6. I have only started really getting into the mechanics in the last 2 years. Buying bikes solely to fix them up. The really confusing thing is that with the bikes I have fixed in the past, they have had similar issues, but always consistent symptoms. This one boggles the mind in that the oil disapears without going anywhere and the coolant loses about 20mL and then is fine...

    I was just out for the last few hours retightening every bolt, checking each for torque. Cleaned of every bit of dirt and grime so any leak of any kind will show. Checked all seals and gaskets very thoroughly. I will let it sit over night and any left over oil in the pan will drain in the morning and put some fresh oil and give it a shot. This oil was much lighter again after running for much longer than the last couple of times. I found a suspect smudge on the right exhaust running under the clutch cover plate. The bolts were all slightly under torqued and it is actually a '95 model cover on an '88 engine (they are slightly different covers). So having inspected the gasket and redone all the bolts on that side more thoroughly and cleaned all the dirt away (there wasn't much but what there was I made sure was gone) we will see if that solves it. My current hypothesis and I realyl hope I am right, is that the oil was dripping from one of the bottom bolts to the exhaust and smoking off and up the front fo the engine. Disguising the cause of the oil loss and making it look suspiciously smokey around the exhaust ports. I am still skeptical because the smoke was not very oily in any way, by smell or colour =/
  7. Takea sample of oil and send it to a laboratory. Chemical analysis can diagnose whether coolant is in the oil and tell you whether the problem is head/headgasket.

    It won't take much water to turn the oil milky.

    Only other explanation is a load of water sitting in the sump that isn't coming out with each flush (oil and water don't mix very well).

    If you need details for an oil testing lab send me a PM
  8. A thorough test and I could not find the cause of the mysterious white steam, pressure tested the cooling system. Very slow leak identified, but no sign as to where. Put through some chem-i-weld and it seems to have stopped the external plumes of white smoke. I was assuming coolant on my exhausts somewhere...

    Yet to verify if the oil turning milky white is solved. The mechanic I go to said it was probably condensation given the latest results and suggested a thorough flush and a long ride. Apparently the only way to verify if it is serious is to take it out for a good ride up to temp and see if the water evaporates out or something. Does anyone know how good of an idea this is? This mechanic has a very good rep. in my town for always being on the money, but still not sure it is a great idea.
  9. Go for the ride mate! Im sure you couldnt do too much damage... Let us know how you went.
  10. So a final update and finish to this and my other post. Removed the carbies, pulled them to pieces and soaked the lot in carby cleaner and then re-assembled. Everything is working fine :]

    I thought I had cleaned them well enough the first time, but it never hurts to be super sure. And in some cases it even removes hundreds of $$$ of headaches.... Like, in my case, unfortunately after a few hundred dollars =/
  11. Glad to hear you got it sorted