Previa Oil Problems

Hello, I have just found this site and registered.

I own a toyota townace myself (Wich is off the road funnily enough as they are a load of trouble) but a friend of mine who does not have Internet access has a problem with his Previa. We think we know whats wrong but not sure so we were wondering if anyone on here knows better.

There seems to be a reserve Oil chamber (In front of car under bonnet) which you fill up as well as the standard filler for oil on the engine.

We think the Switch on the bottom of the sump is faulty as the Oil light keeps flashing low oil but there is more than enough oil according to the dipstick.

What brought this to his attention was a lot of smoke and rough running and when they checked the Dipstick it was way too high so we think oil was getting in with the Pistons so the fuel mix was completely wrong.

They took some of the oil out so it was right by the dipstick and drove it up the road and once it had burnt the oil out of the pistons it ran fine.

Since then they have noticed a pumping sound comming from somewhere near the reserve oil chamber and what we think is happening is the pump in the reserve oil chamber is always on because the Oil level sender in the sump is faulty so it thinks it is empty. So if you put the right amount of oil in it, and then fill the reserve chamber it just dumps the extra (maybe 2 litres or so) into the engine and causes the oil over filling.

The oil empty light is flashing all the time but the dipstick says it is ok.

We think that if we empty the oil (As it needs a new filter and oil anyway) we could take the Sump oil level switch out (Thats what we think it is anyway but not sure) and test it with a tester.

I am hoping that we would not need to take the sump off to get the Oil level switch out. Although I can see it now, unscrewing the bolts that hold it on and hearing a little clink as the bolts on the other side drop into the sump.

Any ideas on this would be appreciated.

Thanks.

I have the same problem can anyone help ?

i had the exact problem on my TCR11, this is caused by the valve under the reservoir oil tank, i dont remember the proper name of it but basically, the valve is faulty, causing it to open and dump too much oil into the engine. Its costs over £100 from the dealers i believe, best buy second hand.

Does anyone have the proper name so i can order one.

Does anyone have the proper name so i can order one.

Dear All

This is a common problem and can be caused by a number of faults (including ECM failure..!) , but the most frequent one is the failure of the oil-level switch in the sump pan... You can actually identify the fault by accessing the ECM fault codes from the diagnostic connector under the passenger seat...

The oil-reserve tank holds about 2.5 lires of oil, which, when added to an already full engine, is quite enough to cause rough running and even "hydraulicing" as the engine is literally "drowned" in oil...

Easy fix?

Reach under the reserve oil tank and identify the connector that feeds the auto feed system pump, mounted in the bottom of the tank... NOTE; this will probably be the nastiest place on your car - people will have been spilling oil here for years - wear gloves... :(

Pull the connector apart... your auto feeder system is now disabled and you won't suffer from excess oil in your engine any more - just check it every week on the dipstick - I've been doing this for about a year... I keep the tank topped up and just reconnect the connector when I think she needs a little oil adding...

BTW... After years of messing about with cars/bikes I know that this sort of switch normally fails due to corrosion/dirt (there's a lot of condensation and acidic by-products in an engine)... Most respond very well to a little TLC and if the OEM part is over £100, this would convince me to "remove, refurbish, replace"... B) I wouldn't, however, go for a 2nd hand item - You'll be doing this job at the same time as an oil change and you'll need to dump the oil again to get the switch out and back to the scrappy - too much hassle by far...!!

And finally... If you're going to get your hands dirty and try to repair or replace the switch... The Previa sump doesn't have a gasket, it's silicon sealed to the engine block (instant gasket), but the oil level switch has a seal and is held into the sump with 4 bolts - the nuts are captive (welded into the sump) so you can get the switch out without removing the sump... (you may need a new gasket to refit it though...)

have Fun!

Jeff

Thank you Jeff for an extremely thorough and useful solution.