18rgu compression

[bholmberg]

I've recently got an 18rgu home, put it on the engine stand, and was hoping to get it in my car fairly soon - my compression test results are: (#-psi) 1:130, 2:150, 3:170, 4:160
that seems a little bad... i did the oil on the piston test and #1 was still 130. any suggestions as to what next? a friend has suggested pull the head off and send it to a machine shop. If this is my best option, can anyone recommend a shop in eastern melbourne please. Another note: originally planning to spend under $1k if possible. but would extend my budget if required.

[Javal]

I can't recommend anywhere in melbourne, however you may want to have a read of the 18R-G dedicated thread for a bit of info.

Keep in mind that you can't machine the surface of the head very much. It should only be machined for straightness and that is all, as the design of the timing chain tensioner / guides don't allow for bugger all reduction in head thickness. Get the valves lapped / reseated and the stem seals done, you should come in well under your $1k budget.

[bholmberg]

thanks Javal, a good start on information.
if anyone can recommend a machine shop in eastern melbourne, that would be great.

[Javal]

Edit, double post!

[Javal]

No worries mate!

It would seem your woes would be in the top end of the motor if your dry / wet compression readings are the same. Hopefully getting your head reco'd will sort it out! Good luck!

Team 18R-G needs another runner!

[Omegaman]

If able a freshen up also may help.
while on stand maybe a hone and check valve clearances before sending head off for rebuild. A least you can do that yourself and the cost of new rings maybe. Just a thought.

[Silly Rabbit]

I did the same to check my 18RG.......take it to RG Baker Engineering in Clarice Rd in Box Hill....they charged me $500 to strip it and deck it / clean it / re-cut the valves in / stem seals and just generally make sure the head was sound and then re-assembled it.......had that done about 9 months ago so price should be about the same depending on how good / bad yours is....they do good work

[bholmberg]

After much deliberation, I think i'll just bight the bullet, and take it in to rg baker for a rebuild. I'm going to have to do some research on what is worth doing, and might as well do it while everything is easily accessible...

in the last 2 weeks i've purchased a new sporty steering wheel, exedy hd clutch, a set of koni adjustables, and a new battery system - I am really looking forward to getting some time to install my goodies, and will be hanging out on these forums a bit more. getting this 18rgu in the car will be a big step forward for my old ra40. thanks for your help guys.

[bholmberg]

ok, update. i've pretty much rebuilt the whole engine. the head was done by rg baker, and all new gaskets, all cleaned out etc. everything went smoothly and timing setup seems spot on by timing marks - BUT I did a compression test today and I can only get 80psi on all 4...

there is a catch however:
- when i engage the starter motor, no plugs - the engine spins freely, at a good speed.
- then when i insert my compression tester is in 1, the engine basically stops when it gets to that cylinders compression cycle, which makes me think i'm not getting a very accurate compression test.
- Then I put all the sparkplugs in, and the starter can't turn the motor. just a bit of smoke from the electrical connections...

using the same starter motor that got me 170psi on day one, and its running off a brand new 750cca optima battery.

anyone got any suggestions??

[Omegaman]

Check again without plugs that oil pressure increase when primming engine. This is for compression.

I'm no expert, but i would double check timing again. If it is out, it can cause the engine to lock up. Could be 180deg's out.
Someone will jump on shortly and give you more alternatives

[Willofan]

My thoughts to start with the simple stuff and check the battery to starter cables first to make sure they are gettting a good connection (power & earth), make sure the starter is getting a good earth on the block, then the starter motor might have dropped some coils or have dirty brushes.

Then check valve timing as a secondary point.

Is there anyone in melbourne can drop around and have a look for him should all these be OK?? Sometimes the obvious is hard to see until you have a second pair of eyes.

[bholmberg]

thanks for your guesses guys.
- well I headed out the the shed and studied the valve timing, and all 4 strokes seem just right, with 1342 order.
- checked electrical connections again, jumper leads going directly to starter, and voltage seems fine.

weekend I might try another starter, a different wiring method, and another compression tester.

I'm also going to have another good look with a green book and some friends with their 'fresh eyes' this weekend, and I'm almost certain its something basic... Hopefully it is something obvious that is being overlooked.

as for oil pressure, I think there is an oil pressure increase... What is the best way to check if i'm getting oil pressure? the engine is not in a car, should I wire up an oil pressure gauge (engine is not in the car, but sump is full of clean oil). or would i get the same result from putting a capfull of oil down the sparkplug hole and testing if the pressure increases?

anyway, thanks. hopefully i will find the answer this weekend.