Let's solve my 20V conversion problems

[Jezza_hr]

Hi guys, some time ago I converted a 20V into my AE86 and have had considerable amount of problems from the beginning.

When I first installed the engine I was having 2 key issues

- The engine was burning oil above 5k rpm (when the VVT kicks in) at quite a quick rate, I was having to top up the oil every other day. It's also worth noting that the oil pressure was quite high, pushing out the dipstick at high RPM before installing a tougher O-ring

- The water pump was leaking pass the gasket, partly due to using the 16V water pump front with the 20V rear so I could continue to use the viscous fan until I installed an electric one.

After having rebuilt the engine due to the burning oil situation, I'm starting to wonder if the cooling system could be the problem. The problems I now face on the second install are:

- Oil leaking from the front crank oil seal (I will require some advice on the best way to replace this without removing the engine if someone can give any and the most ideal place to get a replacement seal) at a very slow rate. This is a brand new oil seal, but it has been sitting idle over the winter and I don't recall it leaking before then. So this could be either pressure related or the fact the seal has dried up and shrunk over the winter months from lack of use, I would probably go with my first assumption.

- I'm also still facing a slight coolant leak from the water pump (not as excessive as the first time) but this time I'm using the full 20V water pump with new gasket and O-ring and an electric fan. This makes me believe it could be down to a copious amount of pressure in the cooling system which could also be related to the oil leak (and previous burning) due to insufficient engine cooling.

Things of note
- I'm running a BLITZ radiator cap which I believe is a higher pressure than standard, I have recently come to the assumption this could be a culprit. Also, would a thermostat be a possible cause?

-I'm running a standard radiator (with intentions of upgrading to a KOYO, link me if you have an ideal place in which to purchase one from) that may go hand in hand with the rad cap with insufficient cooling.

-I'm also still running in the engine, I've only done about 450 miles since rebuild. I don't know if this may contribute but I thought it might be worth taking note of. I've also been informed that the engine is running quite rich compared to normal by the MOT garage, but then I will sort that out with a remap once the engine has been fully run in.

If anyone has any advice or can help me with my theories it would be highly appreciated. I've had just about enough of these problems now I just want the car to get into a reliable state where I don't have to watch the fluid levels like a hawk and will feel comfortable taking it out on a track without the fear of something failing on me.

Thanks in advance guys

[jondee86]

It sounds as if you have two separate and unrelated problems.

If the front crankshaft oil seal is leaking, there are a number of
possibilities. The housing could be scored/damaged, the shaft sealing
surface could be scratched/scored/grooved, or the seal might have been
damaged during installation. Seal replacement is covered in the FSM, and
you should be able to do the job with the engine in the car. Buy a new
seal from Toyota, or from any reputable industrial bearing and seal shop.

Inspect all the surfaces carefully before installing the new seal, and
position it slightly forward or back from any wear groove in the shaft.
Make sure the seal is pressed a mm or two past the chamfer, and don´t
forget to put a smear of grease on the seal face (rubbing surface).

Waterpump sealing surfaces can get a bit crudded up with corrosion and
pieces of old gasket sticking to them. You need to get them as clean and
flat as possible, and use some ¨ready-gasket¨ type sealer any place
that looks a bit suspect. You could ditch the bling radiator cap for a new
standard Toyota item, and check the thermostat is installed with the
jiggle valve at the top.

20V engines are known to burn a lot of oil when run on thin synthetic
oils. Don´t run anything thinner than the factory recommendation, and
a semi-synthetic from any name supplier should be fine. Likewise, 20V´s
are also known to run rich if they are unhappy about something. A new
O2 sensor often helps, and the ¨leaking capacitors¨ in the factory ECU
has been implicated in a host of poor running issues.

Cheers... jondee86

[Jezza_hr]

As helpful as always Jondee, thank you However, it's worth noting that even running semi synthetic or mineral oil, I was still dealing with oil burning issues prior to rebuild.

I have also taken a lot of care and consideration installing the water pump after the various issues I had first time around, is there any possibility the rad cap could be causing it to seep?

I'm also running an Omex ECU, so I'm guessing a new O2 sensor (which may be feeling the effects from dealing with burnt oil from the first install) and a fresh map might just cover this?

[jondee86]

The primary cause of excessive oil consumption is worn oil control rings.
Once the oil control (oil scraper) rings lose their ability to clean excess oil
from the cylinder walls, an ever increasing amount of oil becomes part of
the combustion process. Blue-grey smoke from the exhaust is a sure sign
of bad rings. If this was your problem, then it would not matter what kind
of oil you were using.

A secondary cause of oil loss is oil vapour carried out through the crank-
case ventilation system by excessive blowby (also caused by worn rings).
This oil also finds its way into the combustion process.

If the engine is in good/average condition, I would consider adding a litre
between changes (@10,000 km) to be acceptable, and having to add a
litre every 1,000 km to be excessive !!! Anecdotal evidence seems to
indicate that using a thin fully synthetic oil on a good/average condition
20V engine can double the oil consumption.

Incidentally, by now your engine should be fully bedded in, and you
should be load cycling it to redline. After a 1,000 miles you could run a
semi-synthetic and expect to add not more than a litre between changes.

Cheers... jondee86

[jondee86]

Using a higher pressure radiator cap means that the cooling system
pressure will rise to a higher than standard value, before the cap opens
and relieves the pressure. This will place a higher pressure on any join
or sealing surface in the cooling system. If the joint is marginal. then you
can expect to find weeping from under hose clips, and from screwed or
bolted joints. Usually, just re-tightening the clips or bolts is enough to take
care of the problem.

Slightly off-topic: the factory designs an engine to run at a certain
temperature. The OEM ECU is configured to apply safety factors once the
design temperature is exceeded. I have never seen any evidence to
suggest that it is a good idea to raise the cooling system maximum
pressure (and hence engine temperature) on a road/sometimes track car.

Cheers... jondee86

[jondee86]

If you are running a programmable ECU, you have the ability to set the
fuel map to whatever A/F ratio you choose. If you also have a WBO2
sensor and gauge, you can also monitor your A/F ratio to see where it
is running rich, and make the appropriate adjustments to the fuel map.
In many cases, the ECU can run closed loop with the WBO2 sensor to
automatically adjust the fuel map to achieve your target A/F ratio.

Factory ECU´s run closed loop with the narrow band sensor, but they rely
on the sensor putting out the correct voltage. If the sensor is old and out
of spec, the ECU can run rich. They also run open loop (and richer) after
about 80% throttle opening (richer for more power and greater cooling).

However, I don´t know if the OMEX does this, or if you O2 sensor is wide
band or narrow band (factory style). If it is narrow band, they are quite
rugged units. If they get carboned up, you can sometimes clean them up
externally with a wire brush, and then heat the sensor end with a butane
torch to bring them back to life. If yours hasn´t been replaced for 50,000
miles its time for a new one

Anyways, a dyno tune will sort out your fuel map.

Cheers... jondee86

PS: Yes, I am on holiday, so I have a bit of time on my hands

[Jezza_hr]

Wow, you really went to town there Jondee, very informative aswell fella. Thanks very much

[jondee86]

I am coming up on 10 years of owning a car that has been driveable
for less than one year during that time !!! It is now idling (but not yet
road driven) on its last and (believe me) final set of modifications.

In the last 10 years I have read and digested countless thousands of
posts on half a dozen sites dedicated to the AE86 and the 4AGE engine.
I have looked at every site selling 4AGE go-fast bits, and considered
the benefits of supercharging, turbocharging, forged internals, carbon
fibre cam covers and $120 oil filler caps !!!

What I have discovered is that everyone has their own idea of the ideal
setup for their AE86. Some want mega power. Some want the perfect
restoration, a grip car, a drifter or just an every day driver. I have no
problem with that... and now I know what I want also

Along the way I have learned a bit about the AE86 and the various
versions of the 4AGE. Some of it from reading about what others have
done, and a lot from working on my own car. So, like a lot of others on
this site, I am happy to pass along what I have learned. It might not
solve your particular problem, but it might help someone else who
happens to read the post now, or at some time in the future.

Cheers... jondee86

[Miguel - Newera]

Here's a source of good modern info on breaking in a newly rebuilt engine. Have recently done the same with a brand new sports bike engine and the results are encouragingly good: http://www.mototuneusa.com/break_in_secrets.htm

I'd recommend a cooler TRD thermostat which is inexpensive. Your mating face for the water pump should be completely flat (check surface against a glass table). A good gasket sealant should work well and cure the problem I should think. Make sure your radiator is well flushed, or replace it - as a lot of gunk can built up inside after 20+ years of use. The rad cap won't make much difference if uprated, it only means your release pressure is higher - but in normal healthy engine operation a rad cap shouldn't release pressure at all, even a standard one.

Sounds like the oil seal may be damaged, maybe careless fitting. Would be unusual for the crank to be damaged and cause leakage. Easy enough to pull it out once you have access from the front (remove the rad) & replace with a new one, taking care to apply a little grease to the surface where the crank will run.

Hopefully that'll cure your problems. 20V conversions can be fun if done well. These respond well to unrestricted intake, uprated valve springs, high lift 304 cams (no VVTi) a good manifold, exhaust and a proper ECU & mapping.

HTH

Miguel.

[Jezza_hr]

Thanks for that input Miguel, more insightful knowledge by some of the top members of the forum

Once everything is all run in and I've put it through its paces, then I will look to getting more from the engine.