RB30 overheating

[moodah]

Hi Guys,

 

Got a quick question; Whats the best way to flush an engine block to clear out any blocked water galleries in the cylinder head? I've dropped in an RB30 and its overheating.. The ECU shuts off before the water temperature sensor in the water outlet reaches operating temperature.

 

I've spent a while troubleshooting this and for the life of me can't get the to get to the correct operating temperature.

 

I've got an ohmmetre plumbed inline with the water temperature sensor in the manifold so I can see what the ohms are currently at, idling the car while it gets hot.

Edited March 23, 2012 by RB26powered74zcar

[rejracer]

It depends on what the block is blocked with.

 

If it's rust, find a product called evap-o-rust. It sounds cheesy, but it works great at dissolving rust in the entire cooling system. If it's just a neglected cooling system flush it with prestone cooling system cleaner. if the block is clogged with bits of silicone and/or old gasket material your best bet is to reverse flush the system with a hose and lots of water.

[moodah]

The engine was sitting in the weather for 3+ years without running. I assume a whole lot of **** was sucked up and lodged into the head.

 

Ill try sticking a garden hose up the heater hose's arse first to see if it can blast any **** out, failing that, Ill see what the local auto parts store has for sale and give it a run through.

[djz]

Is your thermostat opening? What do you mean the ECU shuts off? Is there a bleeder on the inlet manifold or near there somewhere, if you open that does water come out?

[moodah]

Ive tried with two thermostats. Both of which ive tested in heated pots of water to make sure theyre opening. The RB30 one and a VG30 one. Currently there is NO thermostat in the car and this problem still happens. Every time I drain and fill the coolant system I've been properly bleeding the system through both the bleed screws (screw on top of manifold and next to the water temperature sender + thermotime switch).

 

When I say the ECU shuts off, I mean it appears as if the ECU cuts spark to the engine somehow? I didnt think it was possible though on a motor with distributor ignition system, until I checked the wiring diagram.. The tacho sense wire connects to the [tacho], ignition coil, power transistor and ECU. (probably likely it only uses this wire to check engine RPM, not sure if its actually able to kill the earth to the Ignition coil). After it shuts off I am not able to start it again. There is no spark in any of the leads, yet there is still +12v at the power wire into the ignition coil.

 

I've tried changing different leads from ignition coil to Rotor.

I've tried replacing ignition coil. (with spare VG30 one)

I've also replaced the Bosch type Rotor cap (carbon button type) about two weeks ago. (button in old one completely disintegrated.)

I've cleaned rotor head contacts as well.

 

The fuel pump is always running, I've bypassed the ECU to make 100% sure fuel pressure is not the issue.

 

 

 

I did a diagnostic check on the ECU and it told me code 14 (speed sensor circuit). So im wiring it in right now. Im hoping that the ECU will be able to give me some additional info..

[moodah]

Ahhh SNAP. It would appear the Thermotime switch sensor plug was corroded causing an erratic connection to the ECU.. The ECU wont run the engine without it. I'm sure its intended but I don't know why.

 

I only found the issue since I was stuffing about with the temperature sender to try get the dash to read any signal, bumped the thermotime connection while the engine was running, and it stopped running. Puzzled, I tried starting it again and wiggling the plug.. and it came back on. left it a while, wiggled, dead.

 

Anyone know why its designed this way? Id still go with my original guess that its designed to shut off at certain temp in order to prolong engine/head life..