Oil Leak at Oil Vent 97 Challenger 1800

[glenn2726]

Hi all, new to me 1997 Challenger 1800 twin rotary engines owner..noticed oil leak from oil reservoir, upon inspection it seems it is leaking from the oil vent on the line above the oil tank. Do these go bad very often? I ordered replacement part # 275500398, said it was for 98 and up but didn't see any others listed for 97. Thanks in advance for any info.

 

[mikidymac]

It’s possible but it’s typically the grommets or the tank was overfilled. The check valve can be checked by blowing into it. It should let air in but not out.

 

[glenn2726]

Thanks mikidymac, yes I noticed that there was an oil leak somewhere on the tank when I purchased the Doo...upon closer inspection I found it was coming from the top of the oil tank and that valve is the only thing on top of the tank so suspected it. I ordered a new one and will replace and clean all the oil residue from the tank and engine compartment and see what happens when I fire it up next time. I'm trying to figure out why the engineers didn't just put the vent in the top of the tank or oil cap instead of routing the hose up to the top of the tank...seems like there would be less chance of leakage then even if the valve went bad. The tank was full when I bought the Doo and there was signs of past leakage on the tank and engine area below. Once the engine was started and then stopped I checked and there was fresh oil from the vent valve area...so once I replace the valve will check to make sure there is no leak around the grommet also once the tank is pressurized. I read where someone posted that their grommet leaked when their oil cap was too tight..I thought that there was supposed to be pressure in the tank so loosening the cap would be defeating the purpose. Also with the oil leakage I'm wondering what effect it would have on the engines getting enough oil for mixing? I noticed when the engines were started that the exhaust was smoking so I know they are getting oil but how much...Thank you again for your help.

 

[mikidymac]

There is no pressure in the tank. Oil does not circulate either. The tank gravity flows to the oil pump for injection and fills the rotary valve cavity.

 

[glenn2726]

Hey mikidymac, I read somewhere where the valve was there to allow pressure to help oil flow..but I couldn't see how there would be pressure either as it is just basically allowing the air in to fill the gap left by the oil flowing out..also that would keep the tank from collapsing.. the bad valve then allows oil to flow out due to there being no vent to let air in so the oil travels the path of least resistance. Thanks...

 

[mikidymac]

THe valve is there to let air in that the used oil displaces and not let oil out.

 

[snikwad003]

There shouldn't be oil high enough in the tank to come out the vent

 

[glenn2726]

Hi snikwad003, the oil level was not overfilled when I first noticed the leakage and there was brown staining on the tank as well as the top of the motor which showed it had been leaking for some time. Once I determined the leak was coming from the top of the tank the only thing there that could leak oil was the oil tank vent valve. I'll know for sure once I replace the valve. I then noticed that when turning the motors over again when I winterized the boat...again...that there was fresh oil running down the front grommet side of the oil tank and coming from above the tank...right below where the valve is located. I won't know for sure if the grommet is also leaking until I replace the valve...our weather here in the midwest has been holding onto winter and since it is now once again freezing at night I had to winterize the boat again. I know we're all ready for spring and warmer weather.

 

[glenn2726]

Replaced the oil tank vent valve and cleaned up all the old spillage in the engine compartment and after taking the boat out happy to say that took care of the oil leakage. Tested the old valve and it was bad as it allowed air to be blown thru it in both directions.