xaulzan

So the wife sent me out to the store tonight and I decided to take the TII. On the way home I was having fun and getting on it hard, and after pushing up to red line (slightly past, as the buzzer sounded just before I shifted to 2nd gear, only for a second though), I shifted through second and third gear. Then when slowing down for the next stop light, the coolant light came on and the temp and oil pressure both shot all the way up to the stop. I immediately shut the car off and coasted off to the side of the road, where I called a tow truck and had it towed home.
The coolant hose that runs from under the oil filter to the firewall was split and had shot coolant all over that side of the engine compartment. The thing was smoking real bad, but as far as I could tell it was all coolant steam. I checked the oil and its not milky/cloudy and smells good, no coolant smell (I changed the oil earlier today). The thing that really concerns me is the oil pressure going so high, it was all the way up just like the coolant. Shot up in no time at all too, and I didn't even smell coolant till I stopped (had the windows down). The oil pressure has always seemed a little high on this car, it sits around 70 to 80 under power, but I just chalked that up to it being a low mile TII. The temp gauge has never been above 1/4 since I've owned the car. Any body else ever had the oil pressure go all the way up like that? Anything I should look for in this situation? I'll be ordering all new coolant hoses tomorrow.

Black Knight RX7 FC3S

iTrader: (7)

You couldnt have blown your engine from a broken heater hose. I mean its possible if you drove it while it was overheating for a long time or so like 10+ minutes which would cause problems for the coolant seals.

I have never trusted the stock oil pressure gauge and sensor, get a oil pressure tester and if it is at around 60 psi at 3krpm and around 30psi at idle (750rpm) then it should be good.

Logicalbomb

iTrader: (1)

WORD!

Check out www.racingbeat.com he ships slow as ****, but they have a really nice adapter for oil pressure and temp on there that will help you keep track of this a little better. I have seen my oil pressure rise to about 90psi under pressure on the track, and I have had 0 problems with it.

Rob XX 7

iTrader: (8)

90lbs with stock oil system?

A new stock sender is cheap. When new they are accurate, stock gauge always matches my aftermarket, same for the temp gauge

clokker

iTrader: (2)

That's my experience as well...the stock pressure gauge is actually pretty damn accurate (albeit heavily dampened) but folks seem to enjoy doubting them.

amiralawi

This happened to me. You should be all right. The oil pressure sender is right next to the heater hose on the engine side, so some coolant may have gotten in the connector and messed up the reading. Clean it out some and see what it says.

Logicalbomb

iTrader: (1)

There is nothing stock about the setup I use, sorry for that misimpression. Just saying the lines hold up.

xaulzan

Well that makes me feel better! I'm sourcing out some replacement hoses now. What do guys think about the blue silicone hoses, are they worth the extra cash?

Black Knight RX7 FC3S

iTrader: (7)

in all my FCs, I have never gotten one that shows accurately.


I do not know how well silicon hoses as big as the stock heater hose will handle 15psi of hot coolant. I dont think they are rigid enough to handle the pressure.

xaulzan

What about these http://www.racingbeat.com/RX7-1986-1...tem/11483.html for the main radiator hoses? I've decided to replace all the hoses, none of them are dry rotted or anything but neither was the one that failed. Although I did have the brake master cylinder fail last week and spray brake fluid all over that side of the engine. That's probably what weakened that hose.

sharingan 19

iTrader: (16)

Silicon looks cool, but I just don't trust it for the cooling system, I've seen a few get soggy after prolong high temp high heat use. The originals lasted how long? There isn't any long term testing on silicon coolant hoses (that I am aware of) and for the price difference why bother?

xaulzan

Good to know, thanks for the heads up, I just ordered OEM replacement hoses from Mazda.

Logicalbomb

iTrader: (1)

I use silicon upper and lower cooling hoses and have yet to run in to any problems, however I did order in a dual fan setup and am falling aaroncakes installing an E-Fan guide to have them kick on at 165, I also run wetter than water and always a precise 50/50 mix in a koyo racing rad.

As for the oil lines the next big upgrade will always be braided for the oil lines. There is a reason those anodized nozzles and shiny braids are located under rice rocket round the world, and it ain't just looks.

I have heard of silicon getting soggy on hotter engines, but as I run mine at the track during the summer 90-95 degrees I haven't had any overheating problems with the hoses or my system. The stock gauges are fairly accurate but like a doctor it's always good to get a second opinion. Your cockpit may look like the take off sequence to a NASA rocket but you will be the most informed guy on the road, regardless of how much of a tool it may make you look like.

Early warning is always the success to any engine lifespan, and as you have a great eye for when to put the stops to the motor (shown in your quick reactions to pull over and have a toe) I believe aftermarket gauges would suit you to a T as far as giving extra warning/comfort to your ride.

They do get a little expensive, but there are plenty of options out there for you as far as colors analog/digital gauges and mechanical vs electrical. They also have a pretty wide assortment of aftermarket gauge holders and they're pretty easy to install.

I am glad your car isn't **** up right now because every time a rotary dies the world becomes a little more sad of a place to be. Good luck on the fixes, and as always POST PICTURES!

xaulzan

Got the new hoses in today, gonna swap em out over the weekend and see what the damage is.

xaulzan

Ok, so I got sidetracked replacing the CV axles and alternator on the wifes maxima over the weekend, and didnt get to the hoses till today. I replaced all three heater hoses, and the main radiator hoses. Filled the radiator, and started the car with the heater on full to move some coolant. The car started right up, and did its cold start 2800 RPM thing like normal, but the oil pressure shot right up to 110psi, so I shut it down. The only thing I can think is I changed the oil and oil filter last week, and actually blew the hose on the test drive. I put 20w50 oil in it and a napa gold filter. It ran with normal oil pressure until the overheat. What could be causing this???

xaulzan

Im gonna try to test the sender unit tonight, and see what happens. Also, when I removed the air filter the rubber around it was melted on the corners, and created a sticky tacky mess that ran all down the around the airbox.

RotaryRocket88

iTrader: (7)

Blowing that heater hose is dangerous. I've told the story many times now, but I had an engine crack the water jacket within about 10 seconds of that hose exploding. A giant cloud of steam started pouring out of the engine bay, the temperature gauge pegged, and the engine shut itself off before I had a chance to do anything. After replacing the hose, the engine would overheat after idling for only a few minutes. When we took it apart, the water jacket around the heater hose connection was destroyed. Hopefully you got lucky, but there's no guarantee until you see if the engine will run without overheating.

For the oil pressure, if the wire to the sender is somehow grounding out, it'll peg the pressure gauge.

xaulzan

Ok, thats probably whats going on then, because it pegs all the way to the right as soon as I start it, way past the highest line, up around the words "psi". I guess I'll go try to run it again, and see what happens. Thanks for the heads up.

xaulzan

The thing Im worried about is the possibility of a cracked water jacket pumping coolant through the area where the sending unit is and causing the high reading, because it doesn't do it when the key is in the on position, only after the engine is started.

Molotovman

iTrader: (49)

If your oil pressure was that high it would be blowing by your oil control rings. You would be having a lot of blue smoke.

StevenL5975

Hi,
I got the same problem with my car, after heating up to op. temp the car was followed by a cloud of smoke on the highway. I barely had time to check the gauges (which were normal at the moment) the low coolant buzzer came on...

Cause was the already mentioned, ruptured heater core hose (under oil filter) near engine block.
That caused the engine to pour out half the coolant. Lucky I did shut it down immediatly. Mine was smoking real bad too.

You might be lucky and it was just the hose failing, I heard from similar situations a few times, apparently these hoses are prone to leak/break with oil contact.

Best regards
steven

cfamilyfix

iTrader: (15)

This happened to me me years ago on a 85 12a. The heater hose blew out on the highway right next to the oil filter bee hive...had the car towed and repaired. The engine lived on but it always smoked on start up after that...

xaulzan

Well, I haven't been able to track down a mechanical oil pressure gauge, so I just risked it and ran it for about 20 minutes. It seemed to run fine, temp gauge goes to about the 1/4 mark where it used to sit, not smoking no steam. The oil pressure went all the way up to the "o" as soon as I started the car, but everything seemed to work fine. I guess I should order a new sending unit.

J5sense

iTrader: (3)

check the wiring on the sending unit. its prob grounded out.

xaulzan

Well, Ive checked the wiring on the sending unit and it seems fine. Im starting to think that the sending unit itself is bad, because its now acting like it used to, only the displayed range is higher (like from 95-120 or so) and when you first start the car it reads normal for a second. Everything else seems to run fine, only my boost isnt as good as it was before. Im still reading -200mmHg of vacuum at idle, but my boost range is only peaking at 200mmHg to 250 mmHg, whereas it used to consistently get 300+ mmHg at boost in every gear but 1st. I think I may have an intake leak or something now. I had to remove the airbox and intercooler to get at the heater hoses. At least the motors still good (knock on wood...).