# Compression test results - R32 - good?



## dragyth (Oct 21, 2008)

Just compression tested my R32, engine was warm but lost a bit of heat due to standing while I took some engine components out...

1. 127
2. 130
3. 129
4. 130
5. 140
6. 140

They all seem a little low, car's covered 80k miles, these were performed without any oil in the cyls. Good? Bad?


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## dragyth (Oct 21, 2008)

Stupidly I did 3 cranks on first four and 5 cranks on the last two. Which would explain the higher compression on the last two cyls. First time compression tester.

Should I be at all concerned by the compression? Taken from the results above I can guesstimate that it'd be around 140 all across the board had I done 5 cranks.

D'OH and i had spark plugs in all five holes apart from the one i was testing at the time. is this also wrong? Sorry about all the questions - I've never needed to compression test any of my previous 18 cars but with the Skyline I felt like getting it done!


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## dragyth (Oct 21, 2008)

Re-did it properly and got this

160
158
158
140
140
90

The battery completely died when I was doing the last one - hence 90. I hope that's why the other two were low in comparison, but drawing from the two results above, looks like I have a reasonable engine? What are the tolorences for a 'good' rb26?


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## Marky_GTSt (Dec 31, 2005)

You need to remove all spark plugs for the test, and use a wide open throttle and the same number of cranks each time. (Its a good idea to remove the fuel pump fuse or unplug the injectors) Take the readings, then put a small amount of oil down each bore and retake.

Its hard to compare you'r readings if the test conditions are different. 

I would say they are all a touch low myself. Im not sure what others will think but I would have expected a bit more. Maybe retesting them in the way I described will give more accurate readings.


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## dragyth (Oct 21, 2008)

Marky_GTSt said:


> You need to remove all spark plugs for the test, and use a wide open throttle and the same number of cranks each time. (Its a good idea to remove the fuel pump fuse or unplug the injectors) Take the readings, then put a small amount of oil down each bore and retake.
> 
> Its hard to compare you'r readings if the test conditions are different.
> 
> I would say they are all a touch low myself. Im not sure what others will think but I would have expected a bit more. Maybe retesting them in the way I described will give more accurate readings.


Yep re-did and got 158, 160, 160, 140, 140, then the battery died so 90!

Are those first five within the parameters of a 'good' rb26?

Battery's on charge now so will give it a good smash tomorrow on those last four


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## Marky_GTSt (Dec 31, 2005)

Ah, you beat me 

160 is more like what I would expect. But its not a complete test and the battery could have been the cause of the 140`s as well. Would be worth charging it and checking the last 3 cylinders again I think.


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## Marky_GTSt (Dec 31, 2005)

I would say if they are all over 150 you will be fine. even 140 is ok...


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## dragyth (Oct 21, 2008)

Marky_GTSt said:


> I would say if they are all over 150 you will be fine. even 140 is ok...


If the middle two are still 140 after a fully charged battery - perform a leakdown test? Would the car still be OK to drive?


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## Marky_GTSt (Dec 31, 2005)

Yes, 140 is fine, even 130 would be ok, below that I would consider taking further action.

If the car didnt missfire and the plugs look healthy then yes, it should be fine. Main thing is, they are all similar figures and none of them are 0


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## dragyth (Oct 21, 2008)

Marky_GTSt said:


> Yes, 140 is fine, even 130 would be ok, below that I would consider taking further action.
> 
> If the car didnt missfire and the plugs look healthy then yes, it should be fine. Main thing is, they are all similar figures and none of them are 0


Car has two dead injectors and drives like a three wheeled Labrador that keeps having spasms.

That said, for 4 cyls i'm surprised it drives at all. I only did about 100m in it to see if it runs before I diagnosed the injector issues.

Thanks for your help. I'll just leave this here:


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## Marky_GTSt (Dec 31, 2005)

I didnt realise the injector post was yours too 

I have the figures for the comp test somewhere, both lower acceptable and difference between cylinders allowed, I just looked but cant place my hand on them right now...


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## Marky_GTSt (Dec 31, 2005)

Ah, it seems for a new RB26 its [email protected], So 150 to 160 is very healthy for an engine that age/mileage. I suspect the results you get on a full battery might be a bit better yet.


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## dragyth (Oct 21, 2008)

Marky_GTSt said:


> Ah, it seems for a new RB26 its [email protected], So 150 to 160 is very healthy for an engine that age/mileage. I suspect the results you get on a full battery might be a bit better yet.


Some great news for once! I got this R32 for £3500 fully road legal (tax MOT tyres etc..) and was expecting the worst - as you do for an 'as seen' 22 year old japanese sports car, so I'm really chuffed even at 140psi.


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## Marky_GTSt (Dec 31, 2005)

Here, more info to make this thread a bit more complete...



> 117 psi @ 300rpm is the service limit **Apparently its 128psi not 117 for the lower limit**
> 171 psi @ 300rpm is the brand new number
> 135+ is healthy still if it's an older engine.
> 
> you are allowed 17 psi wariance from the higest cylinder to the lowest.


The RB25 should be 5 psi higher.


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## dragyth (Oct 21, 2008)

Marky_GTSt said:


> Here, more info to make this thread a bit more complete...
> 
> 
> 
> The RB25 should be 5 psi higher.


RB25 has higher compression? makes sense.

Ok thanks. Just for the record I'm RB26.  I am Jack's cold sweat.


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## wildboy (May 2, 2010)

Always amazes me that a 20yr old engine with 90k on it, with some abuse obviously lol, and my comp tests were 155 on cyl 1, 160-165 on the other five.

Get your battery charged mate and I'm sure you'll be looking at a bargain for £3500.
Don't be tempted to cut corners and start ragging it until you've covered every inch and had it all checked/confirmed as working 100%.
Do it right first time and many happy years motoring are ahead of you.

Edit, if you buy second hand injectors, look at getting them ultrasonically cleaned before fitting them, any small blockage will run a cylinder lean and spoil all your hard work to date


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## MS33 (Jun 27, 2007)

Hi guys, hope you don't mind me jumping in on this thread?

I recently did a compression check on mine, R33 GTR. The pressures were 174-178psi across the cylinders, she doesn't smoke, use any oil and has a start up oil pressure of 6+kg/cm2 and warm at 70mph/3000rpm/5th gear 4kg/cm2.

Do you think the engine has been rebuilt? I do have most of the cars history, except for the ownership of the guy that imported it into the UK.


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## dragyth (Oct 21, 2008)

MS33 said:


> Hi guys, hope you don't mind me jumping in on this thread?
> 
> I recently did a compression check on mine, R33 GTR. The pressures were 174-178psi across the cylinders, she doesn't smoke, use any oil and has a start up oil pressure of 6+kg/cm2 and warm at 70mph/3000rpm/5th gear 4kg/cm2.
> 
> Do you think the engine has been rebuilt? I do have most of the cars history, except for the ownership of the guy that imported it into the UK.


Hah dude isn't standard compression 171psi? Yes I'd say it definitely has been rebuilt, either that or has covered very low miles and has been cared for immensely.
Your oil pressure reading is insane.


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## MS33 (Jun 27, 2007)

Hi mate, covered 98000mls now, the guy that owned it was a USAF mechanic, so he may have rebuilt it.


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## dragyth (Oct 21, 2008)

MS33 said:


> Hi mate, covered 98000mls now, the guy that owned it was a USAF mechanic, so he may have rebuilt it.


Yeah that's going to be rebuilt. I would vouch that my car was fairly typical of age for a non-rebuilt and it's done around 82k miles. I was getting 160 on the first three before the battery was dying, and I was impressed at that.


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## MS33 (Jun 27, 2007)

dragyth said:


> Yeah that's going to be rebuilt. I would vouch that my car was fairly typical of age for a non-rebuilt and it's done around 82k miles. I was getting 160 on the first three before the battery was dying, and I was impressed at that.


I did think it had been rebuilt, but it's nice too get some input on the subject. :thumbsup:


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## dragyth (Oct 21, 2008)

MS33 said:


> I did think it had been rebuilt, but it's nice too get some input on the subject. :thumbsup:


I had an SR20 rebuilt once and it had an HKS head gasket, the gasket had a little tab coming out the side with HKS on it. Any signs of this, or related stuff?


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## MS33 (Jun 27, 2007)

dragyth said:


> I had an SR20 rebuilt once and it had an HKS head gasket, the gasket had a little tab coming out the side with HKS on it. Any signs of this, or related stuff?


I've never seen anything like that, will have a check tomorrow for anything that may point to a rebuild. Never thought to look for that sort of thing. Cheers.


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