Hi guys -

Recently picked up a very nice S4 NA for under 500 bucks. Runs well, aside from the the creeping overheating. Also kind of weird how the blower only blows cold/room temp air, even when it's on full hot.

What I did already was:

- Flush old coolant. It was brown. Gross.
- Add water and some peak flush stuff.
- Drove around for a few hours.
- Flushed again -- clear water was now brown. Still gross.

I've done this process several times, and every time it seems to get a bit better. But the problem, ultimately, still persists. Also want to note, I've never let it get higher than 3/4 of the way on the heat gauge and the coolant buzzer has never gone off.

So I guess the engine itself has some sort of residue or "coke" on it that is causing the engine to slowly overheat? Should I use a mixture of water and acid to remove whatever is in the engine?

Any advice would be helpful. Thanks!

 

Is it rust or one of the stop-leak addatives?
Also, use the block drain plug near the driver's side motor mount. You'll get more of the old fluid out than if you use the radiator drain plug. I'd just flush it normally without addatives, since I am unaware if how it may affect your coolant seals.
Replace your thermostat if you suspect it is gunked up and may help your overheating issue.

Your heater core is probably filled with that same stuff and preventing it from heating up all the way. It could also be the air mix motor or logicon not routing air over the heater core. Try flushing the heater core.

 

Time for rebuild.?

 

Rx7 stock guage has three positions- cold/normal/fuked. Never let it go past half. I learned the hard way a decade back. On s5 don't even let it get to half. It sits a hair under. Send it to kevin landers and get it fixed.

 

sounds like air pockets.. shout laundry detregent and a good rinse will help clean out the sludge

 

people still send their motors to kevin?

 

I did. Why?

 

Is the logicon working correctly? Listen to see if you hear a door move when switching from hot to cold.

Also when you drive it try to baby it around and see if it still overheats. I had a coolant hose that would only leak when put under pressure ie gassed it or reved real high (above 3+)

 

figured he was hurting after all the hokey **** we had seen before he left this forum in a huff over the switch of ownership and advertising requirements. like welded n/a exhaust port sleeves in an FD engine with other misc used parts for $3k.

 

I've pretty much been babying it from the get-go because the clutch is completely shot. (I mean, seriously dead).

I pulled the thermostat tonight and it looked like this:


I can only imagine this gunk is all throughout the internals. Anything viable for removing it?

 

I do not know. But he did my engine and it is very strong. But I did no mods at all and used all top quality seals and mazda apex seals. He seemed pretty busy to me.

 

aint cool to talk **** about the guy when he isnt posting here

 

You can rent what's called a "block tester" from any parts store. This won't work if you have exhaust leaks or do this in a garage, as the solution detects combustion gasses. You can test (properly, might I add) for blown coolant seals this way. Just leave the radiator cap off and use the sniffer to check for combustion gasses in the coolant. I'd do that before getting too far with all those flushes. Do change out that thermostat though. Mazda OEM, all the way. Bad things happen when you use any other brand... I've had my own experience with that.

 

fit the correct s4 thermostat and bleed the radiator from the screw on side of top hose spout
a bad thermostat not only does not open fully
,, it recirculates the hot water for another lap ,, as the bottom of the thermostat is a bypass hole plug


make sure the pressure relief cap is on the point that has the overflow hose to the bottle
the point is either on the thermostat neck , on top of the radiator ( if late rad )
or remote in front of the rad ( if very early rad )

as for the heater,, the control unit , motor , or thermostat controller maybe faulty
if you cant work it out then you can flip it manually

if you stick your head under the dash you can flip the linkage off the side of the valve and operate the valve manually to full open or full shut position

 

Agreed.

OP- Try some white vinegar on that thermostat. See if the scum comes off after it soaks for 24-48hrs.
If so, I'd flush your coolant system with white vinegar. Google it. It breaks down calcium deposits and cleans out the scum pretty well. I let it sit in radiators with calcium build up for 24hrs then flush it out both ways with a garden hose. Lots of deposits come out.

If you want help with a rebuild pm me, we're basically neighbors.

 

OK - I'll pick up some vinegar on the way home from work.

The gasket was also pretty much destroyed. I picked up some high temp RTV to form a new one. How long should I wait for it to cure before driving? 24 hours?

 

Replaced thermostat - flushed engine, runs like a dream...

Until I hit red lights. It takes a LONG time to heat up, but it gets hot if I sit still. Warm air comes out of the logicon now, and if I keep the car moving, it's bang on at 1/3 temp gauge.

So I'm thinking the clutch fan is shot? Any other ideas?

(When it warms up to 1/2, and I then start driving, the temp falls -- So the radiator and thermostat must be doing their jobs correctly)

Edit: Also, replaced thermostat with an OEM one, not a stant.

 

on S4 models its normal for the temp gauge to read under half

 

Yeah - I know. That's what it is when the car is in motion.

However, at a standstill, it rises until the car moves again.

 

nothing is keeping him from coming back that i know of.

just because someone opts not to or doesn't care to defend themself doesn't mean that it can't be brought up, that's just a rediculous point of view... should i hypothetically go and rip off a bunch of people and then leave the forum? i guess it shouldn't be discussed afterwards because i don't come back to defend myself? that's straight up ignorant.

who's to say he won't try and come back and rip on me? then again i'll simply post pictures of that FD engine with welded exhaust port sleeves, i simply don't know how he can defend that one. chunks of metal going through the turbos generally isn't good for them. it was lazy and cheap, too cheap.

 

Do you have a fan and does it work? Fan shroud? Plastic under-tray?




As a side note, the radiator (in my opinion) for the Rx7 was SEVERELY under developed. The engineers that designed this car did not (once again, in my opinion) give it a nearly large enough radiator. People who live in the south routinely have issues with this (such as myself). A larger radiator and a properly working cooling fan is what should be in any Rx7 owner's near future, if not already done.

 

Yeah, I have a fan, shroud, and undertray. The fan spins like it is supposed to, however I'm not sure if the clutch functions 100%.

I'm looking into an e-fan solution anyway.

 

I used a Hayden 16" single speed fan. You can get one from any parts store. 2 speed is overrated.

This is how I made the fan shroud:

https://www.rx7club.com/2nd-gen-archive-72/diy-electric-fan-shroud-808292/

 

When I first got my koyo rad I drive around for a week w/ no fan at all! As long as I wasnt sitting still temp was between 1/4 (proper stock position) and 1/3 ....and that was on a T2.

Certainly sounds like a fan issue, if you are looking into efans check out the mercury villager/nissan quest fan. Its got a great shroud, draws less amps than the taurus (although I would upgrade from the shitty s4 alt before any efan swap) and blows like a tornado even on the low speed (like -10° in 10 sec)

 

my car is n/a so maybe thats it, but during the nc summers I dont have a huge cooling issue with stock fan and rad even while drifting. After a few consecutive laps itll eventually get to 212*, but I would expect that from full throttle and little air getting across.