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Hey gang.. So I just picked up a 93 rs for $400. Next step is a bp(t) swap, and atx - mtx conversion. Going to post a worklog here pretty soon.

Anyway, the sohc in it now overheats. I spent a good amount of time searching, and reading up... here's what has been done.

The previous owner took the head off, had it machined, and replaced the head gasket. I just got it, so until today, I haven't had a chance to check it out. I stopped by Autozone and picked up a new thermostat (The previous guy said he replaced that as well) and gasket.
The garage was locked, so I didn't have tools. I figured I try some of the things I read on here before replacing the thermostat until the garage was opened up.

To took off the radiator cap, and fired it up with the heat blasting. I couldn't really see the fluid moving around, other than from what appeard to be the vibration of the engine running. While doing this, I did notice the fluid overflowing. The bottom hose got warm pretty fast, but the top on stayed fairly cool.

Feeling the hose, I noticed that there wasn't a wire (the one that kicks on the fan I presume). Then I noticed another wire spliced, and wired up to a switch next to the dimmer wheel and mirror controls.
There IS a CEL.



So, after about 5 minutes, I checked out the temp gauge and flipped the switch to turn on the fan.



I didn't want to let it get any hotter at that point, so I shut it off and let the fan run to cool it back down.
So from what my n00b a--- can tell, my first guess is that the coolant isn't flowing. I don't see any leaks, oil or coolant. The oil is very clean, as it the coolant.

What should my next step be? Replace the thermostat and hook the wiring up correctly?

Ok, because my best guess is that the coolant isn't getting past the thermostat, I'm going to just take it out, and see if it overheats...

Any other ideas are most welcome ; )

Update

I took out the thermostat, put the housing back on and fired it up.
I had accidentally broken the temp sensor wire while taking the housing off so as you can guess, I got pretty excited when the temp gauge didn't rocket up. Then I realized it wasn't moving at all.

So I fixed that, and started it up again. Still overheating.

Any ideas from here? I'm at a loss...

Dead water pump my friend.

If you removed the thermostat and the temp is rising and that hose isnt heating up on one side then its not moving the water.

ho bag wrote:Dead water pump my friend.

If you removed the thermostat and the temp is rising and that hose isnt heating up on one side then its not moving the water.

I was thinking that would be my next step. Is there a way I can tell if the pump is bad once I get it off (I imagine I can turn the pulley with my hand, and see if somethings moving or not)?

Is your heater blowing hot air once it gets warmed up? If not then definitely the water pump. Water wont get circulated into the heater core if the pump is malfunctioning. Also check to ensure the belt is tight on the water pump.

Tunes67

Tunes67 wrote:Is your heater blowing hot air once it gets warmed up? If not then definitely the water pump. Water wont get circulated into the heater core if the pump is malfunctioning. Also check to ensure the belt is tight on the water pump.

Tunes67

Actually, no it isn't. I meant to post that before I went on vacation.
I see the timing belt is also on the water pump... Is that just a pulley, or what?
Pardon my non mechanic questions
I don't need to redo my timing or anything like that once I swap it out, right?

You shouldnt be able to see the timing belt.. it will be covered by the black plastic belt cover on the passenger side of the engine. The alternator belt also spins the waterpump. But the timing belt is hidden from view. Off hand.. I dont recall if you have to remove the timing belt to get to the waterpump in the B6 engine.. you do in the K8 (V6 cars) but its been a while since I have had that timing cover shroud off. You can find more information on water pump removal in the online shop manual. The shop manual is for a 95 which has a different engine than yours. However.. the waterpump location should be the same with only minor differences. Here is a link to the shop manual.

http://www.mx-3.com/95manual/index.cfm

Tunes67

Yes, it should have a cover, but it does not... according to the chilton book, the timing belt idler pulley needs to come off... I'll let you know how it goes

There is probally a bubble around your water pump for sure.


What you need to do is wait for the car to cool down a bit and then take the radiator cap off. (Youll need someone in the car for this) Get them to start the car and let it idle to get up to temp. Watch the coolant level to see if it bounces, Have a big jug of water with you while you do this. If the level ever goes below the very top then fill it again. Youll have to park somewhere where it wont matter if coolant gets spilled because its going to happen. Let the car idle and idle and occasionaly you can rev it up a bit by moving the throttle with your hand. The coolant level will go up and down and eventually after the filling and reving it should eventually catch the bubble and youll get a surge on scalding hot coolant coming out of the radiator. Youll have to tell your friend to shut the car off once you see this start to happen. For gods sake keep your face and hands clear of the radiator cap because it can happen at any moment.

When you check your coolant what color is it? It should be a nice green if its rusty then you probally dont have a water pump left in there. You shouldent be running straight water because that will rust out the inside of your enigne.

I know all about coolant problems. Have a look at the pump that came out of my engine when I was rebuilding it over winter.



and here is what it is supposed to look like.



My car never overheated with a pump this bad so yours would have to be worse than this.