I went to Sebring yesterday and the cars first track session although I have been Autocrossing it for over 3 years (about 50 events/80 days). The car handled like a dream but the engine/drivetrain did not do so well.

Car mods: Coilovers, sway bars, light wheels and sticky street tires, cobb tune (10K rev limit) Stage 1 clutch, brake pads and a few other minor mods.

Here are the problems I had on the track and what I plan to do to fix them if you know better or can offer some insight please let me know and I will update the thread as I gather information. I am really looking for people with actual track experience to answer these questions, but open to all feedback.

1. Engine coolant sprayed out of the top of the coolant reservoir.

I have ordered a new cap which will hopefully have a stronger spring. I am also going to drain the coolant and flush the engine. Then replace with 80-90% water 10-20% coolant.

2. Car went into limp mode at the end of the second session, I got a code which was something like "oil omp pump error "

I changed my maps back to the stock map which seemed to run better. I have been using the recommended 2/20 conventional oil and premixing but I think I need a heavier oil.
What do you recommend for the Rx8 in Florida on the track?

3.The car has been having difficulty getting into 2nd gear especially at higher revs for a while, on the track it also started to struggle getting into 3rd.

I have already changed the master, clutch line & trans fluid (AC Delco with Friction modifier). I think this may be a Slave issue so I have ordered a clutch slave.

4. When I was driving home I set off from the lights and had heard a thud like a jolt to the drive train and after that the clutch started slipping.

It does not feel like the clutch is worn out as it is only about 18 months old and it went too quickly last time I noticed it start to slip in 6th and get progressively worse this went from no slip to being undrivable in about a mile of 2. I think I am going to have to remove the transmission and take a look but if anyone hae any bright ideas I would love to hear them.

Thanks for your help, again I will research and work on the car and update the thread as I resolve each issue.

 

1. i'd have a look at the sealing surface of the coolant tank too, any dirt/gunk on the sealing surface will cause this too. also possible the tank is telling you its nearing the end of its life

2. oils, attached is a page from the Idemitsu oil study on the R26B, as you can see there are a bunch of tradeoffs, Mazda chose the heaviest oil, the 153mm2/s, which is just below a 50weight.

 

Thanks for the info. The clutch is out and completely destroyed so I am ordering another one and also getting a racing beat flywheel while I am in there.

Whilst disconnecting the coolant bottle I cracked the nosel on the top of the radiator which connect to the small hose on the bottom of the reservoir so I am going to replace the radiator with an aluminum one. The nosel seemed to have dry rot as us just crumbled :-(

I think I will give the coolant reservoir a good clean out and hopefully that will be ok.

 

Yea the radiator thing happens a lot. Just happened to me last month. I started one job ended up doing three others. Out of all the stuff I have read on this site, I never came across brittle nipple on radiator lol. Oh well I gained some valuable knowledge while doing the work. Make sure you put foam around the edges and bottom of the radiator or it will not work properly.

 

1. Engine coolant sprayed out of the top of the coolant reservoir.

This is an overheating problem if it came out the overflow tube, if it came out of the cap area then try new cap, if that doesn't work, try replacing reservoir. But if it came out the vent tube, just throwing a higher pressure cap on will most likely not solve your issue. Flush the system, make sure everything is working good, and that the radiator is sealed properly so that entering air has no other choice but to go through the radiator. I have tons of track time on my stock radiator cap and have never boiled over. I use a mix of 20% Zerex Pink Asian Vehicle coolant, 80% distilled water and bottle of Amsoil coolant boost which is just a surfactant. Similar to Redline Water Wetter or Royal Purple Ice.

2. Car went into limp mode at the end of the second session, I got a code which was something like "oil omp pump error "

Most likely OMP failure, this should not be ignored.

For oil weight, you will get a TON of different views, but 5w-20 at track temps gets SUPER thin. I like diesel oil. I use Rotella in everything. Rotella T-6 Synthetic 5w-40 in the Miata and the conventional 15w-40 for the RX-8 in the white bottles, it is cheap and has tons of ZDDP for great anti-wear properties. It's similar to the Valvoline Convential Racing Oil which I also like in 20w-50 flavor but the Rotella is much cheaper.

3.The car has been having difficulty getting into 2nd gear especially at higher revs for a while, on the track it also started to struggle getting into 3rd.

The AC Delco with Friction modifier (I thought friction modifiers were only for certain limited slips?!) might be an issue. Replace with something else and see if the problem gets better. I like Amsoil GL4 synthetic trans fluid, or there's always Redline MT-90. Might just be that your synchros are shot, the S1 trans doesn't stand up to track time very well. The S2 trans is a much better option.

4. When I was driving home I set off from the lights and had heard a thud like a jolt to the drive train and after that the clutch started slipping.

No idea on this one man, might have to pull the trans off and see what the hell is going on in there.


EDIT: After reading your second post, that sucks about the clutch. Kinda figured it came apart. About the radiator nipple, same damn thing happened to me. What radiator are you going with? I'm trying out a different manufacturer for mine, should be here this week. PM me if you want details.

 

1. It came out the cap. I have ordered a MS cap, Thermostat with a lower temperature & The radiator was just an ebay one not sure of the model. When I start putting it all back together I will definitely use more water.

2. Thanks for the tip with the oil, I will look at the 15/40 & 20w 50 and try one of those.

3. I have decided to change the clutch and slave (already changed the master & steel line about 10K back) I will put it back together and see how it goes it I still have trouble I will keep my eye open for either an S2 transmission or an S1 with the intention of rebuilding.
I got the AC Delco idea from the S2000 boys who swear by the stuff, when I started to use it the grinding was significantly reduced but came back over time.

4. I ordered a Racing Beat flywheel (12lbs) and a new clutch disk. The pressure plate still looks new so I am just going to clean it up and reuse it and change the pilot bearing.

Thanks for the advice, the good thing about things breaking is we get to upgrade :-)

 

Can you provide more info on adding foam around the radiator. What is the purpose to stop the air going around the radiator or some type of insulation?

I am also building a Locost (Lotus 7 Replica) and have not seen anyone adding foam around the radiators. Here is my build thread if you are interested. LocostUSA.com • View topic - Paul's Supra 2000 Locost

 

Basically, the efficiency of a given radiator is directly related to how much air can move through it. How much air moves through is entirely based on the pressure differential from the high pressure side to the low pressure side. The higher the pressure in front and the lower the pressure behind the more air will flow through. Allowing the air another path to go to reach that low pressure zone that ISN'T through the radiator is directly reducing the radiators efficiency. Foam is usually the simplest to implement, but many serious track guys end up crafting their own shrouds our of tin / aluminum / abs / etc...

 

Oh right I understand, I will see what I can do I have a welder and a load of thin steel laying around as well as a lot of foam so I am sure I can put something together.

 

1. Engine coolant sprayed out of the top of the coolant reservoir.

This happens to me too. Mine is coming out of the overflow hose though. Do you know what your temps are? I use about 80% water and the rest water wetter and FL-22 coolant.

2. Car went into limp mode at the end of the second session, I got a code which was something like "oil omp pump error "

Not sure about the error but I use Royal Purple 20w50.

3.The car has been having difficulty getting into 2nd gear especially at higher revs for a while, on the track it also started to struggle getting into 3rd.

For the longest time I had similar issues downshifting from 4th to 3rd before a sweeper. I switched from Redline MT-90 to Eneos 75w90 and it got a little better. Then i picked up a cheap second hand Ingalls torque dampener thing to see if it helped keep the drive train in place. Much to my surprise I no longer have shifting issues. So either its the damper or witchcraft. Either way I'm happy.

 

your clutch was coming apart and this is likely the shifting issue as well

as long as you run regular coolant it will spray out when hot, the only real solution is a waterless coolant that doesn't boil which isn't really a solution on a daily driver, new cap, reservoir,etc. won't make any difference in my experience

OMP error has nothing to do with the engine oil type/weight/etc, wtf people ... the OMP has no way to know if it even has oil period. An error indicates an internal plunger positioning or positioning switch malfunction.

track is not like autox, you are stressing everything continuously for long periods of time, this will take it's toll on any weak link

throwing parts at something without proper diagnosis = phail, or in this case 3xphail

 

My temperatures were getting to about 205F after the first 2 sessions but after I put the stock map back on it stayed around 190F and no coolant spray.

The clutch came apart on the flywheel side and I currently have the transmission sitting on my work bench in the garage waiting for parts. I have ordered the petit light weight flywheel as well as, I hope enough parts to get everything fixed, flywheel, clutch, slave cylinder, radiator, fluids, radiator cap etc.

@TeamRX8 if the OMP error indicates an internal plunger positioning or positioning switch malfunction. what can I do to rectify that.

"track is not like autox, you are stressing everything continuously for long periods of time, this will take it's toll on any weak link" I really noticed that Autocross is harder on the Suspension and tires, but the track really tests the engine and everything else.

 

205 is fine. Fix for the omp is to replace it.

 

The OMP is over $1000 :-( that is going to have to wait for the time being. I will replace it is the code comes back again.

 

See if one pops up in the classifieds in a part out. It's cheaper than a new motor...

 

@ wright...

The foam also keeps the hot engine bay air in the engine bay, instead of the fans blowing it back in front of the radiator. Check my sig for the $100 thread. The foam is in there, as well as a fans on low mod I used when I am at the track.

If it were me, I would do the heavier oil recommended above, get a custom tune for your COBB, and stay away from the 10K stuff. BTW, I have almost 90,000 miles on my engine, with 30 or so road course track days, lately with 10 sessions a day (daughter also driving my car).

And, interested in Dark Side in November? It is up at Roebling, usually a good RX8 showing from the GA RX8 Club...

 

I bought the Rotella 15W-40 Oil although it is not in the car yet I will do that last.

The Radiator arrived and is a perfect fit so I am very happy with it. It took me about 1.5 hour s to install but I still need to add the foam and coolant check for leaks etc. I also noticed that the coolant reservoir thread is on its way out so I will have to replace the bottle at some point.

Still waiting for the Petit flywheel to arrive before I can put it all back together.

 

see attachment for some OMP info

you can try and adjust the OMP switch, the info is in this thread but you will need to look for posts by myself and dannobre near the end of it. Some of the info at the beginning is inaccurate.


https://www.rx8club.com/series-i-maj...tments-120276/



.

 

Great info thanks Team that explains why the car went into limp mode on at the end of the 2nd session.

 

if you do need a OMP I might have 2 used ones coming off 2 engines. they should work cuz it was pulled from a working car.

As for the boiled over thing, it doesn't matter what cap you use, like team said unless u go with waterless coolant it will boil no matter what. if u want best cooling without the heavy price tag on waterless coolant, just use 100% distilled and add a bottle of water wetter kind of thing to it. but make sure you change it soon or else it will rust.

speaking of radiator cap, I just noticed mine failed as well, I saw air bubbles coming out from top of the cap where the sticker is, gonna use my ARC cap for now.

 

I am going to take mine off and check it. The car went into limp mode once and then was fine for 2 more sessions without any problems. I will stick with the one I have for now and if I have more issues I will contact you & thanks for the offer.

 

Well I added a load of foam around the radiator so that should help force the air through it. What sort of temperature would be ideal for track conditions.

I did some testing on the highway (prior to foam installation) and the car sat right around 200 (degree F) for most of the journey. I simulated track conditions (we best I could legally) by driving in 3rd gear around 7-8K RPM and the temp kept rising at about 216 I went back into 6th as I didn't want to push it.

What is a safe high temperature for the engine to be at before I need to start backing off the power to cool the engine. My buddy said 230 - 240 depending on the car. Anyone have good a recommendation for the Rx8.

 

I pull off track if I get to 235.

I guess you'll find out if that shitty Chinese eBay radiator was worth skimping on at your next event.

 

Well I wanted to follow up it looks like things are still not right. When I remove the cap and rev the engine you can see bubbles coming through the coolant reservoir they are about the size your finger tip and as one hits the top the next one appears. I have pressure tested the coolant system and the pressure is good.

I just went to Bay Bottom Crawl which it a 2 1/2 mile autocross with speeds just over 100mph and I had coolant blowing out of the tank on every run.
When I drive on the road at normal speed there it no problem the Cobb reads healthy engine temps between 180 - 210 depending on outside temperature and speed.

I think the problem may be with the "O" ring where exhaust gasses are leaking into the engine, however I have not seen any white smoke, not sweet smell from the coolant and cannot smell exhaust fumes in the coolant, which are all supposed tell tale signs. I can get my hands on a compression tester to test the rotors, any Ideas what else it might be.

I am still under warranty so before going to the dealer I will remove engine tune & replace cat the only other thing I am worried about is the Light weight flywheel, will that effect the warranty?
Does anyone know if they will let you do the engine yourself, that would be nice as I could port it to and maybe make a pony or two extra if I get a reman from them and take back the dead engine.

 

If you're seeing bubbles it's most likely because the coolant seal blew on the side of the motor where it is making compression, the pressure there will always be higher than the cooling system there so no coolant will get back into the combustion part of the motor.

As far as warranty, it really depends on the dealer whether they will void it or not because of certain aftermarket parts.

And no they will not let you do the motor yourself if it is getting covered under warranty.