Hey everyone, I think I may have hurt my motor this weekend.



I run in the SCCA IT7 class.



In my Saturday race (40 mile sprint), I was pretty much glued to the bumper of another car, and my oil temps were minimum 245 and got up to about 270 max.



On Sunday, My qualifying pace was 1.5 seconds off my best race lap from Sat. Same tires, etc, no changes to the setup at all. The rest of the field qualified faster than their Saturday best lap by about a second - so the track seemed a little faster on Sunday morning.



Then in the Sunday race, I was an additional 2-3 seconds off pace. This is on a 3.27 mile course. I ran different tires, which were certainly a factor, but I was losing multiple car lengths on the straights against cars that were 3-4 seconds off my pace on Sat. It didn't seem like they had a run on me at the start of the straight - hard to know for sure.



One other point, the ambient temps on Sunday were 20 degrees lower, and my oil never saw more than 220-230 deg.



The motor ran fine, sounded fine, started a little sluggish - but no big deal at all, no smoke, no water loss, good oil press, etc, just didn't seem to pull as hard.





Is there some type of failure related to high oil temps that could cause the motor to go soft? I haven't had a chance to do a comp test yet, or even check the plugs.



Thanks,

Neil

 

what apex seals are in there? iron or carbons?



thinking maybe it warped seals?

 

Makes side seals bind in my experience. Sometimes the rotors expand too much and touch the irons also, also hurting the side seals and the irons they seal too..

 

Do a hot and cold compression check and cut open the filter and check for rotor bearing.



Lynn E. Hanover

 

Cut open your oil filter and open up the paper element. If there are ANY flecks of copper present your engine has run a bearing. High oil temp will do that. Its cheaper to check now than waiting until your engine starts knocking.



EDIT: Like Lynn already said! (just read your post again)

 

Well, looks like I'll be building a motor.



I didn't see any metal in the oil filter, so hopefully I can re-use the rotating assembly.



But the compression tested pretty bad:



Front

75 psi cold, 80 hot - schrader valve closed

3 bumps @ 60 psi valve open



Rear

65 psi cold, 70 hot - schrader valve closed

1 bump @ 60 psi, 2 bumps @ 40-ish valve open



The starter wasn't turning the engine too fast, but obviously something's going on with the rear rotor.



Oh well, this was a mazda reman from 1994 with about 20k street miles and 14 race weekends on it - I think I got my money's worth from it!



Anything in particular to check on the "re-usable" parts since the oil temps went so high?

 

this sounds really dumb, but just follow the fsm, or the competition prep book. i think theres a link to the comp book in the faq's

 

I am not as knowledgeable as others that have already posted in the thread, but I would think higher oil temps would lead to higher rotor temps that would cause the sideseals to expand and wear at a rapid rate.



So, I guess I am saying my money is on really big sideseal clearances reducing your performance and/or sacked out apex, sideseal and cornerseal springs.