RB30 Facts, Figures and Helpful Hints

[mudnut]

I recommend getting your RB30 rebuilt by a mechanic that has experience in racing. The only problem I've had is that my new engine died above 4300 rpm. I replaced the fuel filter and took it for a drive. A hell of a lot more grunt, but still dying. I found that one of the rev limiter springs in the dissy button had snapped. I reworked and fitted the spring before giving it another drive. It goes like a cut cat. Very happy with that.

[mudnut]

Had a big problem after the rebuild. The extra vacuum created by the port and polishing to the head, caused the steel air deflector under the second stage of the carby to break off.
The sheet metal component broke apart and was crunched by the pistons. Luckily for me, the metal is very soft and caused minimal damage. The deflector is there to help mix the exhaust gases fed in by the EGR valve, with the fuel air from the carby.

I have cut and filed of the remaining pieces of the deflector. I will have to obtain a deflector so I can maybe fabricate one with thicker steel, so that it will not fail again.

[RickGQ]

This is the Air Intake Pre-heat assembly fitted to a stock RB30S.

When the engine is cold, vacuum is applied to the diaphragm inside the silver unit on top of the air intake.

This unit has a small arm which operates a flap that closes the normal air intake and opens the "Stove Pipe".

The Stove pipe is attached to the metal shroud which collects hot air from around the exhaust manifold.

Vacuum pressure to the diaphragm is halted as the engine heats up, so the flap closes the stove pipe and opens the normal air intake.

The Pre-heat system must be operational for the vehicle to pass a roadworthy.

To prevent the pre-heat flap from opening during a trip where I am likely to encounter water crossings or dusty conditions, I take the normal hose off and stop up the holes with the two plugged pieces. (2nd picture).

Another simple way to block the hose is with an appropriately sized ball bearing.

As I live in a cooler climate, and have had to remove the heater grid positioned at the base of the carby (It had started to disintegrate and pieces were falling into the engine) For normal driving I keep the pre-heat system operational as it helps the engine warm up quickly to normal running temperature.

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Thank you all for this very useful thread on the RB30S.
My personal vehicle is a TD42, however I've inherited Dad's ST30, which is pretty much in original factory condition.
Right now I'm in the process of cleaning things up and sorting out a few ignition issues, it's got a bit of a miss.. Plugs and leads are on order.

In the meantime I've been looking at why it runs badly in cold damp weather. Turns out the intake pre-heat has been disabled - a ball bearing in the hose.
That's simple enough to fix - but - I think one of the mechanisms inside the air cleaner has also been damaged.
Can anyone school me on what these two are supposed to do?
The one with the plastic housing is most likely a temperature sensor valve. What's the other one though, marked '2X14'? Presently it just allows manifold vacuum to be bypassed directly to the intake.
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[mudnut]

Follow the hose under the filter housing. If it is only missing at idle check for a vacuum leak. If you remove the ball bearing in the pre heat, you will hear the flap open when you put on and pop off the hose. To see if the flap is ok, vacuum will appear at the hole in the bottom of the filter housing when the hose is attached .

[RickGQ]

Thanks Mudnut,

This RB30 is a bit new to me, having been in a diesel for so long.

I tested the pre-heat actuator, the mechanism operates ok. So, once the ball bearing is removed and the sensor is fixed, it ought to help with cold running.

The miss occurs at all revs and under load, also it's quite repetitive, so I'm assuming it's missing on one or two cylinders.
Measuring the leads, they are ~10k except #5 and #6 which are over 22k.
The distributor was quite dirty inside. I've cleaned it all up and tested the advance is operating ok.

I still need to check the plugs. Have to run out and get a 16mm socket for that.
Once the electrics are sorted I hope the engine will return to its normal smooth running operation.

Last time I even looked at a petrol engine was in 1989 or there about. An old Hilux with the 18R engine. Takes me back.

[mudnut]

Before taking out the plugs, use a bit of pipe to fit over them and vacuum out any crud that will fall into the cylinder.

[RickGQ]

I saw your advice on that vacuum cleaner trick, and did exactly that!
Still a bit of rubbish came out with the plugs... there was some oil or grease holding it in there I think.

[RickGQ]

Thanks to this thread, and helpful posts from Mudnut and Dom, I've got Dad's ST30 Patrol running sweetly again.

The sensors inside the air cleaner control the warm air intake, and had been blocked off at some stage, probably in a misguided attempt to disable emission controls. This would explain why the vehicle ran poorly in cold, wet weather. I've restored these sensors and the warm air intake now operates correctly. The image below shows how the vacuum hoses are run.
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New plugs and leads. The old leads were the cause of the engine misfiring. They were the original leads, dated 1992...
The new plugs and leads are all genuine NGK.
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Thanks to Mudnut for the post about using a piece of hose to thread the plugs in. This really is an easy and safe method to ensure the plugs are correctly installed and not cross-threaded. I was concerned about damaging the alloy head, this method eliminates that potential issue.
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After a good spray with carby cleaner, the RB30 is revving easier as well. That carby cleaner is like magic.
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I'm very impressed with how smoothly this engine runs. It sounds like a well oiled sewing machine.

[mudnut]

A carby kit would be a good investment. The rubber components dry and go brittle with age.

Check the condition of the small fuel hose that feeds the carby.

They are well known for cracking and leaking. I could not find a replacement anywhere so I bought a piece of hose and six hose clamps. Two to clamp the hose ends. The other four keep the hose from kinking as you form the curve, but don't over tighten them.

[RickGQ]

The carby has had a kit put in it at some stage - I can see the screws have been removed by someone in the past. Dad can't remember exactly when though.
The short fuel hose is ok, perhaps it was replaced when the carby was serviced.
I'm sort of at the stage where I should find a new home for this ST30 and go back to driving the red TD42. The more work I do on the RB30, the less I'll want to part with it! Tempting to play around with it though hey?