dorkman52000

Okay, I just finished putting S5 tails in my S4, and I was driving home from my parents' house. I was going down this long hill in neutral because I was behind a semi and all of a sudden the "check coolant level" light came on the cluster, as well as that annoying buzzer. Still going down this hill, I noticed that my coolant temp gauge was increasing rapidly, even though I had no load on the engine and my E-fan was on. I pulled over at the bottom of the hill (only spot available) and shut the engine off.

I opened the hod and noticed that there was coolant dripping from somewhere on the backside of the engine, possibly under the UIM (it was hard to tell during dusk and some ******** broke into my car last week and stole my maglite). ALSO, there was a boiling/hissing sound in the same area of the engine but no steam at all. The upper hose was hot, but the top of the radiator wasn't. I opened the cap slowly so I could release the pressure, and there was a significant loss of coolant in the radiator. Basically, I couldn't see any coolant above the first row.

So, my engine runs smoothly, but I'm afraid that maybe I blew a coolant seal. The car has 212,500 miles on it as of this morning, and I knew that I was going to get a rebuild eventually, but I wanted to make sure with you all first that a rebuild is in my "forseeable future." I did a search, but no one else seems to have had exactly the same problem I had tonight.

What should I do next? Start taking the engine out? Or is this just a coolant problem? I am going to work on it tomorrow, but I want to make sure I start in the right place. Thanks for all your help, I'll be checking this thread continuously throughout the evening.

89tracerman

if you want a qick temporary fix i would suggest some CRC block weld

RotaryEvolution

iTrader: (30)

if there is a external coolant leak then i would locate and fix that problem, you could do the rebuild if you want but i would at least find and fix the coolant leak first and be sure it isn't leaking externally from the engine any longer.

jhammons01

89????^^^Wha?? (not you Karack you slipped in under me)

You blew a rear coolant hose. Try replacing your coolant HOSE that runs to the top of the intake. Fill the cooling system (a procedure for filling is found in the archives) and see if you have any more problems.

A cooling write up in on Aaroncakes website.

89tracerman

my bad i read coolant seal, and thats the first thing i thought about
dont listen to me im just a noob

jhammons01

No worries

dorkman52000

That seems like a good place to start. I know how to fill the system, but I haven't yet changed out the rear coolant hose. You're not talking about the heater hose, right? You're talking about a hose that runs under the manifold? What exactly do I have to do in order to get it off? Do I have to remove the UIM or anything?

Sorry for asking so many questions, I just want to know what I have to do to start working on it tomorrow. Thanks for the replies, by the way

rs_1101

odds are its a bad hose externally. if you think its internal, pull the spark plugs and check for rust.
the reason you car overheated was because the coolant level got so low that there was no coolant return. thats why the car overheated in neutral with no load. if it happens again, hold the car at at least 3krpm in neutral. the temperature will drop.

dorkman52000

Ok, so assuming this hose is the only thing I have to replace:
Is the engine still okay even after the temp gauge got so high? I know that rotaries are not friends with extreme heat.
I'm going to check the plugs tomorrow as well, is there anything else I should check? I should be able to obtain a Mazda compression tester from the dealership where I used to work. Other than compression checking and plug checking, what else should I check?

jhammons01

You say you saw the temp rise. If you did and you turned it off right away you should be OK. You said the engine runs OK. You should be able to start it and run it for a while B4 the temp rises again. If it runs OK then your fine.

There are two hoses that go/come out of the intake. The upper one snakes around the outside of the intakes back to the back of the water pump. The lower one goes under the UIM. I have not tried to take the hose off with out removing all that so somebody else will have to answer that question.

dorkman52000

Okay, well thanks for helping to clear everything up for me. Yeah, the gauge got almost up to the top before I had the chance to shut off the engine at the base of the hill. That's why I'm worried about the condition of the block itself, and I figured that maybe the whole cause was a coolant seal, but the car didn't smoke at all (either from the engine bay or the rear pipes). I guess I'll start taking off the hoses tomorow. I'm still really bummed out. This car's been a real champ, even with its high mileage!
I know I may not need a rebuild, but if I do, I'd like to get an s5 engine to put in there and have it streetported. Is this fairly easy to do? I can swap an engine no problem, but I've never had to put in a newer model engine into an older car (s4 to s5). Basically, I am not sure what I would have to do to get it to run correctly with the s4 computer.
Well, thanks to all who helped me out tonight. I'll post my findings in the next few days.

TII '87

haaaaaaaaaaa mazda's coolant line from hell...

is everyone talking about this relatively small L shaped one that goes from the rear iron to the TB?

if yes, I recommend you to perform the full TB mod and then tap the passages ( this coolant line only warms the TB and supply coolant to the BAC valve )

this hose is really a bitch to remove, and is EVEN MORE a bitch to install if you buy and original hose

what i first did was to plug a longer hose in there, which gave me some room to plug it on both sides...

hope this helps

88 GTU

ahh perfect timing i was waiting for this subject to come up. Look at the one in my car see the chunk missing what should i do with that?

jhammons01

If your hose and clamp go over that hole then your fine. Mine has one of those on the upper part. I did cause a leak until I put new hose and clamp. Now it is solid.

dorkman52000

Man, that sucks to hear. I haven't checked as of yet because it's raining outside here, and we're working on rebuilding my sister's Trans Am in the garage. So, there's two hoses to check from the backside of the engine: one that runs to the rear of the w/p housing (I know which one that is because I removed it from the front in order to replace the w/p housing before), and this newly infamous one that everyone is talking about that goes from the top of the rear iron to the TB.

I am going to look up the procedure for modifying the TB....I've looked at it once before, but its been a while, and I don't remember exactly how to do it. is there a thread that is a how-to that someone can post the shortcut to? I'm going to keep looking in the meantime, but I was hoping someone had the instructions off hand and could easily post them. Thanks for your help!

dorkman52000

Nevermind, I found it:
http://fc3spro.com/TECH/HOWTO/TBM/tbm.html

Cool.