Clean thick oil in throttle body?!

Status
Not open for further replies.
Joined
Feb 12, 2014
Messages
734
Location
Gold Coast, QL, Australia
My car has had trouble starting for a fair few months now and is mainly in the morning after sitting all night, and it's only been getting worse.
At first I thought my fuel pump was low on pressure, but it would fire straight up if i pressed the gas pedal. This made me think there was carbon or something blocking the throttle plate so i took the air hose off and my theory was right, only it wasn't carbon but thick clean oil pooled at the bottom of the throttle plate! This of course wouldn't allow air through and wouldn't allow the engine to start without opening the throttle a bit...
So I've found my problem but the questions have changed!
How the [censored] did it get there? Since the PVC system is attached after the TB
And what could it be? It was way thicker than the 10w30 engine oil, almost had the same viscosity as lucas stabilizer
I have been running UCLs in strong doses but don't see how that would get there haha
 
Yea many cars get build up in the throttle body, its almost considered normal. Now some cars suck in more oil than others but that is on a case by case bases.


I get the CRC mass air flow cleaner and clean the MAF. Then spray out the throttle body and PCV vacuum line with carb cleaner. Then start the car and spray into a vacuum line while the car runs. I do this every 10k or once a year.
For those with DI cars that are known to have dirty valve issues this is a must do IMO, but even those with port injected cars cleaning the intake and throttle body helps as well.
 
Sounds like the Upper Cylinder Lube's are settling between starts(overnight) and being sucked into the Throttle Body(TB).

Here's my story:

I overdose my '80 Firebird(in my signature) with Sta-Bil & Marvel Mystery Oil(8 oz/ea) over the winter. When I finally start the car/engine in the Spring when I take the car out for the Summer, I always have to remove the air cleaner cover and wipe out the pool of RED fluid/lube from the Sta-Bil & MMO. They're both red like ATF.

These are much thinner fluids than most UCL's but, it's still there/present! They must be settling(sometime during the winter) and upon the 1st Springtime startup, gets sucked in, from the gas tank into/through the carb and sprays/coughs itself into the air cleaner housing.

The engine starts fine in the Springtime after sitting for up to 7-8 months. And this doesn't happen at all during the Summer months even though I use the same dosage of Sta-Bil/MMO for each tankful of gas throughout those months.

Your situation with the Upper Cylinder Lube(UCL) may be happening sooner(overnight) and for now, I'd stop using the UCL!
 
Last edited:
Try gumout fuel system cleaner or chevron they both have PEA in them and suppose to do a good job cleaning your fuel system.
 
So, on quite a few cars there is a coating from the factory on the inside of the throttle body.

You need to use a proper throttle body cleaner that will not remove this coating.

I know it was on a lot of fords, and I'm pretty sure my toyota has a sticker stating that it has coating as well.
 
Guys. His cars are fuel injected so it's not possible that anything added to the fuel is building up in the throttle body. I'm pretty sure it's the pcv valve sucking in vapourized oil and it's building up.
Get a catch can. Problem solved.
To clean the existing mess up I'd remove the dirty parts and clean them with carb cleaner or something like that. You could Seafoam it but then all that gunk will be going into the engine which will likely foul plugs and make a mess on the valves.
 
Hi guys thanks for all the replies, i think i have found the culprit. The oil is entering through the crankcase breather pipe connected to the air hose just before the throttle body.
I think the cause is a useless PCV valve. I replaced the OEM plastic one because it was old (but probably still worked well) with a new metal one. One thing I noticed was that the metal one rattled which was because the valve inside was pretty loose and didn't make a tight closed seal like the old plastic one did. I will try find an OEM plastic one and see if that makes a difference because I never had this problem with the old one
 
And yes a quick google search returned thousands of results about it being pretty normal and sometimes can be caused by worn rings and blow by. I know this is not my case because the engine only has around 190,000km, still has full compression and doesn't use a drop of oil between changes.
Another note is that i overfilled it by about a pint last OC but i think it's been going on before then
 
All it needs is some full throttle! Seriously, get your foot in it once in a while when hot in a higher gear, it'll self clean.

Bazillions of cars running well without catch cans, no real need for one...
 
I think a lot of WOT driving coupled with a faulty PCV valve is whats causing it! It never happened until a few months ago when I started taking it to high revs on a daily basis. (Never used to go above 2000rpm and got bad carbon buildup) Around the same time I changed to an after market PCV valve which I don't think is ventilating efficiently enough at WOT, causing pressure to build up inside the crank case and be forced out the brether pipe, straight into my throttle body! This would explain why I got white smoke under acceleration once as well (it only ever happened the once) maybe the PCV valve got stuck closed if it is dodgy
 
Status
Not open for further replies.
Back
Top