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| ebspak6 |
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G'day i've just built a new 4.0 and the bl**dy thing blows smoke after engine breaking. ( it's manual)
After i cruise down a hill in 3rd to keep the speed down. when i get to the bottom of the hill, pull up at the lights, put the clutch in and whoof of smoke goes past me. blows a bit on gear changes to. Could it be valve stem seals? excess manifold pressure sucking oil past the seals? its a high comp motor. im not happy jan. Help? |
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| Bert |
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If its a really fresh motor (<200km) I would give it a good hard run then check again after an oil change. If it still blows smoke the builder has done something wrong.
I have done motors which had ~020" lips on the bore and they did not blow smoke but were a little rattly. My motorbike did blow some oil smoke on start up for the first 200km but after its first flogging to 10000rpm it stopped. |
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| Nanger |
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Sounds like stem seals or valve guides. Did you get the head done up. Also you could give the PCV a good clean out in case it has clogged which will also cause this.
_________________ -Dave
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| TIKFORD |
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does sound like valve stem seals. high engine vacume sucking oil into cylinders. has the motor been "run in" yet?
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| ebspak6 |
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TIKFORD wrote: does sound like valve stem seals. high engine vacume sucking oil into cylinders. has the motor been "run in" yet? thanks guys. the motor has done 1500km now. had it's first oil change at 1000km. I had new exhaust guides put in as well as all new valves and seals. it's got EF .020" pistons which are supposed to be higher comp. haven't checked the PCV yet but i will do.
I thought it might be stem seals. can you do them in the car with the head still on? thanks again. |
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| msman |
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stem seals can be done with the head still on, a doco was up a while back that described using a compressor in the sparkplug hole to keep the valve up, do a search i suppose.
_________________ why do u write in here. |
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| EBXR8380 |
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DON'T run synthetic oil in it or any oil with friction modifiers..
If its only on vacuum / slow down sounds like either PCV or guides.... If its auto? Fry stooling it up and check how much blowby it has out filler cap ??...
_________________ As in ZOOM 126 edition |
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| FastFutura |
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Bert wrote: If its a really fresh motor (<200km) I would give it a good hard run then check again after an oil change. If it still blows smoke the builder has done something wrong.
I have done motors which had ~020" lips on the bore and they did not blow smoke but were a little rattly. My motorbike did blow some oil smoke on start up for the first 200km but after its first flogging to 10000rpm it stopped. try give it 10 000 rpm that'll fix it.. promise it wont blow smoke anymore nahh seriously, run it in first give it a good coupla thousand. then run it hard.. but dont cook it b4 its run in.
_________________ 94 ED Futura, 5spd, RPM clutch,3.27 LSD, PH4480 pacemakers, 2.5'' Supercat, STG 2 Wade1004-112 advanced16degrees, XH intake K&N panel,pedders superlows, Expursuit puter. clearindicators, volvoTT thermofan
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| Bert |
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FastFutura wrote: try give it 10 000 rpm that'll fix it.. promise it wont blow smoke anymore
nahh seriously, run it in first give it a good coupla thousand. then run it hard.. but dont cook it b4 its run in. When you run-in a new motor what are you actually running-in??? The only thing that should be doing ANY rubbing are the rings. Apart from a check and adjustment of all systems in the first hours the break-in is critical on the rings. The best way to ensure the rings bed in is run the motor hard. Why do think you have to hone the bores?? If the motor is built right it can and should be run hard from the word go. If anyone thinks I am wrong ask any V8 supercar team, Drag race team, etc how the break in and run their motors. 2000km break in would take forever. Also if anyone argues that their motors are rebuilt regularly look at all the privateers in the Australian Superbike Series. Most of them will do at LEAST one year on the standard motor. My mate thought like you and his motor had no balls and never stopped puffing smoke! |
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| altedxr6 |
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treat it like a baby, it will always been a baby, give it a bit, and she'll be more powerful in the long run .
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| ebspak6 |
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it's running rich as s**t as well. hope that hasn't hurt it. (washing the oil off the bores etc.) i baby'd it for 1000km. Its done almost 2000 now, and i've started to give it some. I gave it a good flogging last night actually. i've got a PCV on order from ford. will fit that on monday. Its a XR motor running on a 3.9 ECU that wouldn't effect it surely?
I've also booked in into blackwood auto and dyno next saturday to get a A/F reading and power run. thanks again. |
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| davids |
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You mention its running rich as sh*t.... Are you running stock ecu?? It shouldnt if map sensor is getting correct vacumn. Also... As for smoke problem... Does it do it more when engine is cold rather than hot or the same amount all round?? If there is a differance with engine temps then its most likely inlet guides. Expansion occurs in the guide when the engine head temp goes up thus closing the tolerance between valve and guide. Doesnt matter how good the seals are if the bloody valve is flopping around like a d**k in a bucket
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| tickford_6 |
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Posts: 6449 Joined: 11th Nov 2004 |
ebspak6 wrote: it's running rich as s**t as well. hope that hasn't hurt it. (washing the oil off the bores etc.) i baby'd it for 1000km. Its done almost 2000 now, and i've started to give it some. I gave it a good flogging last night actually. i've got a PCV on order from ford. will fit that on monday. Its a XR motor running on a 3.9 ECU that wouldn't effect it surely?
I've also booked in into blackwood auto and dyno next saturday to get a A/F reading and power run. thanks again. and there is your problem. you babied the engine from the start up to 1000km. that is the totaly wrong way to run in an engine. never baby a new engine. you have load the engine up to bed the rings in properly. we are not saying redline the thing every where, you pretty much just drive it like you would any other engine, the only thing is make sure you don't sit at one rev for to long. dont cruise at one speed keep slowing down and speeding up. engine i build only get run in for 500km or 2 tanks of fuel. then it's time to have some fun |
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| EBXR8380 |
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Exactly...
Here's more ... http://www.mototuneusa.com/break_in_secrets.htm
_________________ As in ZOOM 126 edition |
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| ebspak6 |
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How i normally drive involves redline in most gears. in my terms "Babying" was nothing over 4000RPM or flat throttle. Most of the time it got average driving. I went for 3 hills drives in the first 500kays.
As for davids reply. it runs a stock 3.9 ECU. I have the XR ECU but no one can tell me how to by-pass smartlock without paying $275. It blows the same amount of smoke hot or cold. It only ever blows smoke after idling for extended periods or engine breaking. both would create high manifold vaccum. I have another MAP sensor i could try to see if it improves the fuel economy. I think only the exhaut guides were replaced. along with new valves and seats. hopefully its just the PCV or the seals. |
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