well long story short, as a result of a bad cat i overheated pretty badly on the way back home lastweek... it got pretty far in the red before i find a safe place to pull over. anyway, i let her cool down on the side of the road for an hour and limped her back home.

so i havent been driving much... it is fine at night, and in the day with the AC on i can keep the temps down. but......i have been having some issues with the secondary turbo not coming online every once in awhile (and blowing smoke after i let off the gas @ high rpm's) so im not sure whats going on with the secondary (looks like it may need a rebuild?? but it could also be due to the backpressure from the clogged cat not letting the secondary flow enough to get spooled).

anyway (this is the worst part) as im coming home tonight i look down at my oil pressure gauge... and at idle its DAMN NEAR 0!!! maybe like 4-5 psi at most at idle... and at 6K im seeing like 30 or 60 psi (sorry i cant remember i just wanted to get home before i absolutely killed the motor)


im not sure what to do now, or what to check for.... im at my wits end with this car because ive spent the last year working on it to get it running to this point, and now im having more and more very serious problems.

i know it needs a new cat (im waiting on trying to get one of the knightsport ones from japan).... and i bet the turbos need to be rebuilt (or replaced).... and this motor is an the original 94 w/ 84K on it and may be time to go soon (i have a spare motor in the garage but im not sure of the condition as of now)... any insight into where to start diagnosing these problems would be supurb.

thanks as always, heath

 

regarding the oil pressure it just might be your sender unit. i remember reading a bunch of posts about how it's inaccurate because the sender is bad, but that you're fine. i don't even look at my oil pressure anymore, as long as she's running i'm happy.

 

hmmmm, the exhaust manifold is pretty weak under extreme heat, you may have cracked it. as for the turbos blowing smoke, they may need a rebuild or a replacement. you are probably in need of a rebuild, and you shouldnt be driving it at all.

 

All you are doing driving it with a clogged cat is asking to blow the engine. Why don't you just fire several .50 cal rounds into it, it will be quicker?

 

Take $50 - $100, go to your local Midas, have them cut off the clogged cat and weld in a straight pipe as a temporary fix.

 

I was going to say too....Having all these probs and still driving around with the clogged cat. Would be a good idea to get a HFC, or as $100T2 said. Just get a stright pipe welded in if you are strapped for cash right now. Seems like if you have a feeling that this is the cause you should take care of it first and see where that takes you....And get an aftermarket temp gauge.

 

yeah, aftermarket temp and boost gauges are on the way... i am buying the cat as soon as we can arange the GB for this knightsports cat. i have a miata that i usually use as a daily driver....... the reason i have the FD is because the miata was out of brakes, so i switched cars when i went home lastweek. i have new pads for the miata and have time to do them now, but the problem is that home is and hour and a half away, so the car needs to make it home!

the overheating i can keep under control long enough to make it home, but oil pressure is a serious problem (if the gauge is showing me the correct pressure). the rest i can deal with (turbo rebuild, new cat) but the car needs to make it home with the propper (or any) oil pressure.

can someone tell me the correct oil pressure at idle, normal driving, and 6K at full boost?? i seem to recall 30psi at idle and normal driving, and when i was really on it i would see 60+psi..... and much much more when the car was cold.

maybe its the oil pump? maybe im loosing oil pressure due to a leak from a bad secondary (if its bad)? i just made sure the oil was topped off and im getting the same problem. i'll check the intake pipes for excessive pools of oil etc. basically i need some help diagnosing this problem with the extreemly low oil pressure

 

More than likely the oil pressure sending unit is flaking out and it's my understanding that oil pump failures on rx7s are pretty rare. My oil pressure gauge used to read 0 psi at idle when warmed up for about 2 years until I replaced the sending unit a month ago.

 

So if RotorMan is having overheating problems, how long till he sees symptoms of coolant o-ring failure?

Not saying you have this, but figured I would throw it out there since one of the most popular replies for things around here is "your coolant seals are gone, new engine time!"

 

As stated, it's just the sender unit. Clean or replace it.

Bouncing needle, and 0 psi at idle are very common. I see it all the time.

The fact of the matter is that there is no way you could have 0 psi of oil pressure at idle w/ a mechanically driven oil pump - presuming you still have oil in the car and no dead spots in the system.

 

clayne, the needle doesnt bounce at all... just really low pressure at idle and as i rev it rises... just not much. is it possible that the oil pump took a crap? or that its on its way out? what were you saying about dead spots?? can you explain (oh yeah and there is plenty of oil).

AMRAAM4, yeah i wonder how long it will take to develop som sort of coolant related problem. (i hate to admit this but when i first got the car 3 years ago i had some "issues" lets say, when i flushed the coolant system. basically i was an uber noob and didnt think to burp it.... car overheated hardcore! although after everything was cooled down and refilled everything was just fine) then i let the car sit for a few months a half year later as i was fixing some vacuum prolems. i started her up, and she blew the hugest cloud of white smoke... i took the cap off of the radiator and she was DRINKING coolant as she ran. i shut her off thinking the motor was done for. i went out a few hours later and tried again... same problem. the next day i tried one last time and nothing at all.... i think the seals possibly had shrunk or something and after warming them up they were ok. that is the only explanation i can think of.... ever since i make sure to start her if she is sitting for more than 2 months. havent had the problem come back.... this motor is a trooper (knock on wood)... but it wont last long with all the current problems.

 

As I recall from the manual, minimum 55 psi @ 3000 rpm. And I agree with a previous reply, if your talking OEM pressure guage, it maybe your sender.

 

Heath, with that many miles on the motor and the types of problems you're having (but you have a spare ride), maybe it's time to start thinking about an engine rebuild and while your at it throw a cheap HFC in there to keep costs down.

 

Your engine does NOT need a rebuild.

It is JUST the oil pressure sending unit.

This is a CHRONIC problem with the OEM sender. Remove it and clean it. If you want to feel extra safe, replace it. But I guarantee you if you see oil pressure rise (especially the needle jumping up to normal) when applying gas, it IS the sending unit.

 

How hot did it get?

 

dont try driving it, just call a tow service, its alot cheaper then, having to fork out on other heat related problems.

 

He may have over heated already...

 

mrrx7, it got pretty freakin hot before i could pull over safely... like into the red on the stock gauge!!! it was fine, and then just shot up very fast... by the time i knew there was a problem it was 3/4 of the way up, and by the time i found a place to pull over it was in the red w/ the coolant light on. i even shut the motor off and cruised down the highway w/ my emergencies on when i saw a place to pull over up ahead. did damage occur? most likely... does it currently run without any obvious problem? yeah. i have a spare motor in i dont know what shape, in my garage if this one dies, or ill just rebuild it if the housings etc are within spec


HEns, yeah i would but it is too far... and with the AC on the whole way it should make it if i take it easy (hopefully)


clayne, thanks! ill pull the sender off tomorow and see if i can clean it.... although im not sure how i would go about cleaning it?? any tips?? there's just a little hole in the canaster right? im not sure how you can clean it, it may have to be replaced.

 

The stock temperature guage is quite slow to react (by design). If it ever moves above the half-way point, you're right on the verge of meltdown. I think red is something like 260 degrees, that must've been fun.

Fix the problem, don't drive it. Towing, while sucky, is your best option. Or just yank the cat altogether on the side of the road I've driven a few times like that. It's loud, and gets the bottom of the car kinda dirty, but....sometimes y'gotta do whatcha gotta do.

 

hmmmm.....wiping the "smoot" of the floor pan, too, not just the rear bumper

Jim would enjoy that

 

ok well i cant find my FSM anywhere!! arrggg... ok i think i know what this thng looks like (i had to swap it on my miata, and it was screwed into the block pretty low)... it was a small black canaster..... does anyone know where this thing is placed in the FD? i took a quick look but couldnt see much (im assuming i need to jack the car up to get to it?) if someone could point me in the right direction it would help alot. thanks heath

 

I agree, the sending unit is $90.00 start with the easiest to get to/cheapest part which is the sending unit. These cars don't have much oil pressure at idle anyways. As far as the overheating problem I would say try to find where the coolant is leaking from if it's overheating. If it seems to be leaking from the housing, you might try something like bars leak, but check to make sure you don't have a cracked radiator, leaky hose, etc.

 

there are no leaks in the radiator system.... everything is fine (i think)...

but where is the oil pressure sending unit?? i don't have my service manual with me...........

 

Turning the AC is only going to put more load on the engine and make your heat problems worse!

edit: FSM is online at http://www.iluvmyrx7.com/

 

yeah, ive tried opening the pdf files like 5 times already... they wont open, and i'm not at home and dont have the FSM with me (if i had it i would have just looked this up!) can anyone please direct me to where the oil sender is located???? if i could look it up i wouldnt be wasting forum space! -heath