Engine problems in RB-30 GQ PAtrol.

Submitted: Tuesday, Jun 07, 2005 at 15:51

ThreadID: 23665 Views:8816 Replies:5 FollowUps:8

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troy35

I have a GQ with an RB-30 engine. lately I have noticed a strange problem with the enige but cannot seem to track down what the cause is. The engine seems to splutter as if the distributor was wet but it only does this every now and again. It may be fine for days and then do it for a day or two and then go back to normal. Also it is more noticable when underload say if I round a corner and only drop to third gear then put my foot down it will mis and carry on until I build up my speed but then will be fine through the top end of the power range. Likewise if I had dropped own to second gear it wouldnt do it around the corner.

On the weekend I went up the Dampier peninsualr road which is dirt all the way. ALl the way up it was fine even towing a heavy trailer. However when we were at the camp site and I was driving around through the bush tracks to the beach I noticed it would miss and carry on in the lower gears. Then on the way home it was okay again until all of a sudden the engine died for 1/2 a second then kept going. It did this randomly three or four time which at first I thought was due to foaming fuel as the road was rough (If your thinking of coming to Broome and going up the Peninsular to Cape leveque think again until they grade the road, its the worst I have ever seen it.)
However it did it once or twie on the bitumen too. Then wehn i got home and drove around later on that night it missed and carried on in the low power range until I build up speed. (IT seems as if once I get over a certain RPM its fine) I know it could be plugs, leads, or even fuel but cannot afford to replace everything without having a better idea. Also why would it be so intermittent?

Anyone have ides on this?

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Reply By: Member - Chrispy (NSW) - Tuesday, Jun 07, 2005 at 16:04

Tuesday, Jun 07, 2005 at 16:04

Troy

Forst things first.

1) Remove the distributor cap and make sure it is not cracked. Cracks attract carbon residue - and this "leaks" away spark. Also make sure that the 6 rotor tip contacts are flat and square on their inner edge. They don't actually "contact" the rotor tip itseld as it spins, but they beed to be awfully close. If they look black and slightly "bubbled", then it's new distributor cap time.

2) Check the end of the dizzy rotor itself. It has to be clean. It must not have any cracks in it either.

3) Leads. Make sure they are clean and not touching anything else that's metal - particularly the air cleaner - as the rear three make their way backwards to the back cylinders. Make sure they don't touch each other if you can.

4) Coil assembly. Make sure all contacts are clean.

5) If you don't have a timing light - get someone who does to check the timing - particularly the vacuum advance.

6) Make sure that all hoses in and around the engine bay are fitted and tight. (vacuum lines especially).

7) Get the carburettor checked and re-built if necessary. Have someone throw a full carby kit at tit and make sure that they electronically clean both the primary AND secondary jets.

AnswerID: 114771

Follow Up By: Member - Chrispy (NSW) - Tuesday, Jun 07, 2005 at 16:12

Tuesday, Jun 07, 2005 at 16:12

...and as Bigbear said - check...or better still - replace... the fuel filter. You may also want to replace the fuel pump - which isn't terribly expensive (14psi or so) and is in the tank under a trapdoor down the back. Lift the carpet to see it.... there a re six (if I remember correctly) screws to remove the flange.

FollowupID: 370590

Follow Up By: troy35 - Tuesday, Jun 07, 2005 at 17:42

Tuesday, Jun 07, 2005 at 17:42

Thanks for the tips Chrispy. There is certainly a lot I can try there without having to start spending money. What do you mena by checking the vacuum advance? I have always checked the timing with the vacuum advance hose disconnected and blocked off. Should I be double checking it with it connected and working afterwards? If so will my manual tell me what it should be?

I have already changed the fuel filter but never touched the fuel pump since Ive had the car.

FollowupID: 370603

Follow Up By: Member - Chrispy (NSW) - Tuesday, Jun 07, 2005 at 18:00

Tuesday, Jun 07, 2005 at 18:00

G'Day Troy :)

Yup - check the timing with the hose off and blocked. You don't want any advance applied at the test RPM.

What I mean by checking the vacuum is that you should check ALL the vacuum lines themselves. If they are hard and cracked they don't work - like they weren't there at all. If they are greasy or oily they can slip off their nipples. If they have had ragged ends cut off they may be too short and slip off under vibration. Make sure the one connected to the underside of the air cleaner is on.

Can't remember what I paid for my fuel pump - around the $70 mark (I think!!!).

FollowupID: 370612

Reply By: Member - Bigbear - Tuesday, Jun 07, 2005 at 16:04

Tuesday, Jun 07, 2005 at 16:04

Try the simple things first. Check plugs, check fuel filter for cleanliness, check leads for cracks etc.
Sometimes these things can be found without spending too much money sometimes they can,t.
Did you enjoy the trip to Cape Leveque?? despite the problems?
Bigbear

AnswerID: 114772

Follow Up By: troy35 - Tuesday, Jun 07, 2005 at 17:52

Tuesday, Jun 07, 2005 at 17:52

Yes I did enjoy the trip. The problems were minor anyway. The car has been playing up for awhile now but as it is so intermittent I didn't worry about it. All the way there is was fine and even most of the trip home. I hoped that the rough road had actually caused the intermittent problem to be a constant problem so it would be easier to find and so far it looks as though it has, although I havent driven the car today yet until I get home from work.
It was good to get away though, we did a bit of fishing, collected some oysters, drank beer around the camp fire, ate lamb shanks cooked in my cobb, swam in crystal clear water and the kids had a ball too. I caught some whiting in my throw net and also some mullet which I used as bait and caught a cod and a blue bone. (didnt get a photo though.)
Its good to get away although I will spend all this week unpacking and cleaning.

FollowupID: 370609

Follow Up By: troy35 - Tuesday, Jun 07, 2005 at 18:19

Tuesday, Jun 07, 2005 at 18:19

Not only that Big bear but despite this being our dry season its been pouring with rain here in Broome for the past 2 hours. It hasn't rained here since early March, although its not the first time we have had winter rain in the dry season.

FollowupID: 370615

Reply By: db courier - Tuesday, Jun 07, 2005 at 16:17

Tuesday, Jun 07, 2005 at 16:17

hi troy, while you are playing around in your distributor, give the distributor shaft a wobble and see if it moves. it may require rebuilding which will give you a intermittent problem with getting spark. if the shaft moves around at all it will need some attention.

AnswerID: 114773

Follow Up By: guzzi - Tuesday, Jun 07, 2005 at 17:07

Tuesday, Jun 07, 2005 at 17:07

Is the RB30 on the GQ injected or carb?
have a good look at all the electrical plugs/connectors in the engine bay, clean, tight no damage ,corrosion etc.
If injected another thing to look at is the crank angle sensor inside the dizzy.
It may be worth it to pull it out and give it a clean, I think its an optical pickup, dust may effect it.
Also check the electrical plug that goes into the dizzy for security, cleanliness and corrosion or any damaged wireing/insulation, all these have caused me grief on a VL commodore with the RB30.
The plug on the airflow sensor should also be checked for cleanliness, security,corrosion and have a look at the airflow meter itself for cleanliness ie inside not covered by dust/mank etc.
If after checking everthing else mentioned in this thread above, it still does it, spend the $130 or so and change the sensor and redo the plug connections with the new ones that come with the sensor and the dizzy top bearing which also come with it.
It may pay to one step at a time until it stops doing it, istead of doing everthing then not knowing what it was that fixed it.
Good luck.

FollowupID: 370596

Follow Up By: Member - Chrispy (NSW) - Tuesday, Jun 07, 2005 at 18:04

Tuesday, Jun 07, 2005 at 18:04

guzzi - the RB-30 in the GQ is carburetted. I've got all the injection gear to put on mine... but have heard along the grapevine that if the carby is well maintined and properly setup - it out-performs those that have been retro-fitted with the original Bosch injection system off a VL or Skyline. Go figure !!

So... no airflow sensor as such...

FollowupID: 370613

Reply By: floyd - Tuesday, Jun 07, 2005 at 17:42

Tuesday, Jun 07, 2005 at 17:42

could be air being sucked into the fuel line causing air bubbles or pockets. Check all fuel hoses between tank and Carb/injector pump. Look for splits, leaks, tight bends, cracked fuel pipe (aluminium parts).

AnswerID: 114787

Follow Up By: troy35 - Tuesday, Jun 07, 2005 at 18:23

Tuesday, Jun 07, 2005 at 18:23

Floyd,

For awhile now I have been tossing between a fuel or electric problem and have decided that it is a electric problem becasue it only seems to do it at the low end of the power range. Once I start to build up rpm it dissapears. If it were fuel wouldnt it be safe to assume that the problem would be worse when more fuel is required????

FollowupID: 370616

Reply By: Gerhardp1 - Tuesday, Jun 07, 2005 at 21:53

Tuesday, Jun 07, 2005 at 21:53

The RB30 is the same as the VL Commodore engine I believe.

If so, then the crank angle sensor and diode in the distributor are possible culprits. This will require checing at your auto electrician.

If it is this, resist the temptation to go with the cheap parts fix that is available and go for the expensive proper parts. The cheap parts will fail in no time as I found out when the Auto electrician tried to dud me by selling me the good stuff and charging the good stuff price but fitting the crap stuff. His excuse was that the good stuff fails sometimes.........

AnswerID: 114829