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k@z3
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Ballarat
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January 2005
18RG oil pressure issue. Fri, 07 January 2005 02:10 Go to next message
Hey guys, got another issue i need help with.
I've rebuilt an 18RG engine with the Yamaha twin cam heads and fitted it to my RA28 Celica. The issue is that the oil pressure drops to nothing at an idle of 800 rpm. it's got a high flow pump and all of the crankcase, rocker cover breathers are correctly installed. An ideas as to what's causing the issue? this is the second rebuild of this engine(as i didn't fit new main bearings on the first rebuild Very Happy ) an i made sure there was no issues with the oil pump. Any common problems i should know of? The oil pressure seems to be fine on anything above idle and i used an original Toyota factory manual for the 18RG when rebuilding. The timing chains, bearings and rings are all new and the bores have been honed. Hope someone can help

Cheers

Stevie K
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drift86levin
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Re: 18RG oil pressure issue. Fri, 07 January 2005 04:49 Go to previous messageGo to next message
i know for a fact that it's supposed to be idle at 950-1000rpm.. maybe you should change the oil your using..
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k@z3
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Re: 18RG oil pressure issue. Fri, 07 January 2005 05:03 Go to previous messageGo to next message
Your right there, but that doesn't seem to resolve the issue. Also the oil is the highest density i could find (can't tell you off the bat what that is Very Happy ). seems to be only at low idle and that included when i upped the RPM to 1200 RPM. Strange, because it's pumpin heaps of pressure as soon as i put my foot on the gas. This baby goes like a Mother and revs to 6000 RPM without breaking a sweat (extractors, solex carbs and ramflow filters - makes it sound like a jet sucking air Very Happy ). Just this one little problem that's got me beat. I'm hoping i can find an "expert" to help me out. Thanks for the quick thinking though, it's the little things that can be missed.

Stevie K.
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Jason
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Re: 18RG oil pressure issue. Fri, 07 January 2005 05:05 Go to previous messageGo to next message
yup wind the idle up and check again. Most likley is the pump being worn if so i have one that is in ok nick just pm me.

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drift86levin
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Re: 18RG oil pressure issue. Fri, 07 January 2005 05:07 Go to previous messageGo to next message
befor the rebuild on mine it used to crack 80psi on cold starts, thats just with GTX2 20w50..then once warm dropped to 60-65psi..dunno what it is now..i got rid of that gauge...it just goes between the 2 lines on the stock gauge!

hope you find out what it is..these arn't cheap to rebuild!
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CelicaRA45
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August 2002
Re: 18RG oil pressure issue. Fri, 07 January 2005 09:31 Go to previous messageGo to next message
there is a bolt that goes near the top chain oil squirter have you put that in also these engines are pron to blow the tiny welsh plugs from the back of the cams check that also .when we checked the top squirter to see we found a bolt missing thats why the oil pressure could be low ,you have to check it running thou it will spray a bit of oil all over the place ,but still you can see if you have left something out
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k@z3
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Re: 18RG oil pressure issue. Fri, 07 January 2005 13:22 Go to previous messageGo to next message
There is no spoon.....

I mean oil leak! Very Happy . I have also worked off the factory manual when putting this engine back together so i know it's done right. Just to recap: there is no oil pressure at idle (anywhere from 800-1200 rpm tested) but as soon as you put your foot on the gas it jumps to 40-60 psi. I have tried this engine with it's original oil pump and a new oil pump so i know the problems not there. The crankcase breather is properly hooked up through the correct valve to the inlet manifold. The valve cover breather is hooked up to the ramflow air filters. All gaskets, bearings, timing chains, valve springs and rings are no more than 1500 k's old, and the engine goes like shit off a shovel! This puppy will happily pull past the 6500 RPM mark if you let it! I am using a high density oil so that can't be the problem, and the oil and filter were replaced 2 weeks ago. The problem seems to be that the pressure in the crank case does not build up until you put your foot on the gas... If there is anything simple i've missed, don't hesitate to add to this topic, but so you know my background, i'm 35 years old and this will be the 17th toyota that i have rebuilt since i was 15, so i kinda know my way around engines, transmissions, whatever. This problem just has me beat and i'm sure there is someone out there in the big wide world who will know the answer, so post away!

Cheers

Stevie K
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allencr
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Re: 18RG oil pressure issue. Fri, 07 January 2005 14:20 Go to previous messageGo to next message
gauge, and/or relief valve and/or pump.

i don't care at all about the breather or timing chain or valve springs or rings or bore condition.

CelicaRA45 has engine specific knowledge - i have none.
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CelicaRA45
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Re: 18RG oil pressure issue. Fri, 07 January 2005 21:46 Go to previous messageGo to next message
are you going by the guage in the car or have you put a mechanical oil pressure guage into the block and are coming up no oil pressure on idle
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YelloRolla
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Re: 18RG oil pressure issue. Fri, 07 January 2005 22:01 Go to previous messageGo to next message
Was the original block reused?
Were the bearings in the cam tunnel replaced? As the rear ones have sticks in the oil holes to block them.
Was the pump pulled apart and re-assembled? If so was the relief spring re-installed?
The welch plug is a good one to consider too. There are plugs in the back of the cams (as stated previously) and there is also a small (19mm) plug at the front of the engine (behind timing case) that blocks an oil gallery - it may have been left out and it doesn't appear in the rebuild book.
Were the grub screws in the crank removed? Were they re-installed?

What else has changed? Has the distributor been removed for direct fire ignition? There are a myriad of small things that it could be.
(another small test that you could do is remove the distributor and drive the oil pump with a long screwdriver in the cordless drill and see if the pump actually loads up)

You need to know 1 thing for sure - if it had oil pressure when you pulled it apart and now it doesn't then the mistake definitely lies with the rebuild.

PM me if you need further help.

[Updated on: Fri, 07 January 2005 22:04]

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k@z3
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Re: 18RG oil pressure issue. Fri, 07 January 2005 22:19 Go to previous messageGo to next message
I'm going by an aftermarket oil pressure gauge mounted inside the car. Also the oil light comes on when there is no pressure reading on the gauge. This engine was from a wreaked toyota corona and i had not seen it running before the rebuild. The quetions i'm getting now are a lot more specific and are going to help with the issue. I can tell you all one thing, I have rebuilt 3 18RC engines and never had this problem before. Now... cam tunnel bearings were not replaced, as the engine was rebuilt because i was told it was smokey, so it got rings, bearings, timing chains and a hone. One pump was from the original motor with the spacer fitted, this was dismanteled and reassembled. Then a new oil pump was primed and fitted on the second go at the rebuild.Welch plugs usually stop water from getting out and the 2 half moon plugs at the back of the cams would create a shit storm of oil flowing up the windscreen of the car if they were misssing so i'm pretty sure i would notice. No changes were made to the crank when fitted, the dizzy is standard and everything else went back where it should. The only thing is that 19mm plug behind the timing case. I am sure i didn't remove it an i work in a "clean room" enviroment, with stainless steel benches wiped down and floors cleaned before i start a project, so i know i didn't "forget" anything. Still, i'll pull the timing case off and have a look. Thanks!!!

Stevie K
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CelicaRA45
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Re: 18RG oil pressure issue. Fri, 07 January 2005 22:26 Go to previous messageGo to next message
steve hello im saying there are 2 welsh plugs that go into the back of the cam shafts if they have poped out it halfs your OIL pressure the only way to see THIS is to take the ROCKER off and START the motor with leads connected to see if that is your PROBLEM
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k@z3
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January 2005
Re: 18RG oil pressure issue. Fri, 07 January 2005 22:36 Go to previous messageGo to next message
Cool!

That makes a lot more sense, i'll have a look this morning and let you know, but as to my reply "i work in a "clean room" enviroment, with stainless steel benches wiped down and floors cleaned before i start a project, so i know i didn't "forget" anything".

Still you never do know....

Thanks Again

Stevie K
Cool Cool Cool

BTW

Are you saying that all oil pressure would be affected or only that at idle?
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CelicaRA45
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Re: 18RG oil pressure issue. Fri, 07 January 2005 22:42 Go to previous messageGo to next message
mainly on idle also check the frt near the oil squirter sometimes people for get to put a bolt in its place .the welsh plugs can pop if there is 2 much oil pressure they will be sitting near the oil return holes in the head
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brett_celicacoupe
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Re: 18RG oil pressure issue. Sat, 08 January 2005 09:01 Go to previous messageGo to next message
YelloRolla wrote on Sat, 08 January 2005 09:01



What else has changed? Has the distributor been removed for direct fire ignition? There are a myriad of small things that it could be.
(another small test that you could do is remove the distributor and drive the oil pump with a long screwdriver in the cordless drill and see if the pump actually loads up)






i was led to belive that the 18r-g actual dizzy does not run the oil pump but instead have a 'dummy' dizzy that houses a shaft which connects to the fuel pump/oil pump cam which goes in the oil pump slot. possibly somethin to investigste there Confused

also, when i was puttiing my 18r-gu back together, i had this bolt bolt that i couldnt find where it went, it was about 12mm long, had a 14mm head, a M10 (i think) thread and a copper washer. that bolt blocks off a oil gallery from the block, located just below the block and behind the t/chain. could possibly be that Confused

BTW: i ran my 18rg for the first time today after a rebuild Very Happy

[Updated on: Sat, 08 January 2005 09:04]

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Steve M
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Re: 18RG oil pressure issue. Sun, 09 January 2005 07:09 Go to previous message
Yeah, check everything that CelicaRA45 has said. They are the most likely things.

My 18rc (HM 5 Star recon 50,000km ago) loses oil pressure to the head anywhere below 900 RPM (moved oil pressure sender to head). I reckon during the rebuild they remachined everything and them didn't use undersize bearings, so it leaks like a bitch inside the engine.

In hot weather when it gets a beating (temp reaches 1/2 way mark) it loses oil pressure to the head then too but below 1500 RPM.
I am glad this engine came with the car, if I'd paid for it I would be pissed, the work done was really, really SHIT.

Brett, you'd be right about the dizzy not running the oil pump, it is the little dummy shaft that does it.

Oil delivery is kinda important so make sure you check very thoroughly the cam welsch plugs and the little bolt/oil squirter just under the top timing damper on the head.

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