endless551

Hi guys... its was a day full of trouble... here goes the scenario.

Was out in Sepang track yesterday. Car could not even complete 2 laps without overheating. Previously, i managed to get 3 hot laps before the water temperature start showing any increase.. Here is what I did between the 2 sessions.

1. Replaced radiator with a copper 3-core (approximately 50mm thick)
2. GTR fuel pump
3. Replaced new spark plugs, previous owner were using non-multiground type plugs.

Can't figure how any of the above mods couldve contributed to that. On my previous outing, boost peaks at about 0.5bar but due to the aging actuator.. car now spikes up to 0.6bar (Turbonetic turbo, not sure which model or A/R ratio). Fueling mods has not been done yet on my car as car was running lean previously, up to 13A/F on peak load btwn 4000-6000 rpm and dips to 12 above 6k rpm. Hence I replaced my fuel filter, installed a gtr fuel pump which gives about 200+++ l/h.

Water temperature rised rapidly after about 2 laps and I backed off and cruised the car till it settles down and went back into the pit. While idling in the pit, car was smoking badly for about 2-3minutes. After that it all cleared out. Initially, I thought the overheating has blew the turbo's oil seal and could've been leaking from there. Brought the car home (journey home no smoke detected) and parked it till this morning. A common scenario of blew turbo would be lots of smoke on morning start up but car started cleanly on first crank without any smoke at all. Brought the car out and had a long drive (>40km) under boost. Car still seems fine and no smoke at all. Everything seems to be back to normal.... I couldn't imagine how engine oil could be ingested into a rotary engine other than coming in from the side seals.. but y it only happened momentarily when the temperature is sky high?? Has anyone ever experienced such thing??

Could all the Guru's out there pls advice on this issue.. If this is going to cost me a rebuild be ready to hear from a 20B monster down under tropical Malaysia. Thanks in advance.

RETed

First, how much miles on the engine?
Recently rebuilt?
High mileage motors will have oil control ring problems - do a high idle test.
Rev to 4kRPM for 15 to 20 seconds in neutral - does it smoke?
If it does, it's the oil control rings.

Second, pull the IC pipes - do you see oil in it?
Oil in the intake / IC is due to bad compressor seal on turbo.

Third, are your emission working?
Specifically the "purge valve" and "PCV"?
If the fittings are plugged, this causes too much pressure in the "crankcase" and causes oil to bypass the compression ring in the turbine section of the turbo.



-Ted

NZConvertible

IIRC you have a FMIC. Very hot ambient temps (i.e. any day in Malaysia...) and reduced radiator effectiveness (due to the FMIC) can easily cause overheating. Was it hotter during the second day at the track? A little creative ducting to get air to the oil cooler and radiator might be required.

endless551

Thanks for the reply guys.

I've done the high idle test and everything seems fine. WIll try to get the rest done/checked soon. As for cooling mentioned, that has been taken note but I can't even figure a way for cooler intake air without cuttting some panels...

lastphaseofthis

iTrader: (8)

just a quick question if it is oil control ring problems, the only solution is to rebuild? will any of those stop smoke treat ments help, this sounds exactly like my problem...

Needa13b

Did you say that you switched the spark plugs from single ground, to one that had 2 or 4 ground prongs? If so, I have heard that spitfire or those kinds of multi spark, spark plugs cause cars to run alot hotter, maybe not noticible in normal driving, but probably really noticable racing. That doesn't explain the smoke though, but if that's what was causing high combustion temperatures, then maybe going back to regular plugs will end whatever it was smoking.

pengarufoo

I'm guessing its just slightly warmer than last time and your boost is spiking higher than last time causing it to overheat worse.

Are you running a thermostat? Straight water for the track? Using water wetter? Antifreeze and Water wetter raise the boiling point and can help prevent overheating if you are getting localized hot spots.

Also what pressure is your radiator cap? If it's stock try increasing it, higher pressure also raises the boiling point and helps keep water against the hot spots.

Is the radiator extremely hot when it overheats? Oil cooler? Do you know your oil temp?

Sideways7

iTrader: (7)

Check for hot spots. If you there are some spots that are quite hot while others are cooler, you could have some blockage in the radiator. My guess is gonna be the oil control rings or turbo compressor seal, though.

endless551

I switched back to the factory spec plugs... 9s and 7s. Previous owner actually was using the normal plugs...

endless551

Yes the factory thermostat is still in there. I'm using up to 50/50 antifreeze and water with Redline water wetter..

Radiator cap is uprated to 1.1bar.

Tried to reach for the radiator to feel the heat distribution along the core but was way too hot to even go near there.. fan is in the way too.. any other way I could have that checked? The radiator is sealed and o way I could open it for cleaning.... but I did used some radiator flush item (MADE IN USA) to thoroughly flushed the cooling system prior to filling up...

endless551

If the 4k 15-20sec test is reliable. THen its definitely not the oil control ring prob... Did it once last night and another one just 20mins ago.. The security guard in the building's parking doesnt seem to like rotary acoustic very much!

NZConvertible

You shouldn't use so much coolant, particularly in your climate. Water has better heat transfer properties than coolant, and Mazda states that a 65/35 water/coolant mix is all you need for ambient temps down to -16degC.

That radiator cap won't be making any difference. Higher pressure has no effect on cooling capacity.

endless551

SO how much do you suggest???

NZConvertible

Exactly what Mazda says. 65/35.

endless551

wasted my Water wetter... just poured in a bottle full last week... dammit!!!!!