Question about engine compression check result

Joined
Apr 3, 2005
Messages
284
Location
Kyunggi, South Korea
Hi,
I did engine compression check several times ago and got below result.

#1 : 175 psi
#2 : 176 psi
#3 : 180 psi
#4 : 182 psi
#5 : 176 psi
#6 : 177 psi

I saw FSM and found that normal compression value of 3F motor is 149 psi but mine is so high.
Here's my procedure.
1. Run engine to reach to normal operating temperature.
2. Remove all six spark plugs,
3. Connect compression guage to #1 spark plug hole.
4. Turning engine about three second.
5. Check value in compression guage.
6. Do 3 to 5 for the last cylinders.

I used reliable Japanese made brand new compression guage.
After checking, I checked again using with other compression guage and got same result.
I couldn't figure out why it's so high than commented value in FSM.
My FJ62 is 1988/06 and I haven't done any valve adjustment until now.
(My 3F motor's valve cover have no experience removing.)
Also this is first compression checking. So I don't have previous checking value.
Regarding mileage, odometer indicates about 140,000 Km, but my father drove 5 years without speedometer cable because of hardness of getting proper parts in South Korea.
So I guess that actual mileage is some more than 200,000 km.

Is there any people who could tell me whether it is normal value or not.

Oh, Min Seok
 
Last edited:

60wag

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It does seem a bit high but if you're not getting any detonation (pinging) I wouldn't worry about it. My first guess would be that the gauge is out of calibration but it sounds like you checked that. Has the head ever been off the engine? Maybe the head was shaved to up the compression. Or maybe you've got a ton of carbon buildup on the pistons? You ca look in the spark plug hole with the pistion up and see the top of the piston.
 

nikos8

 
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I average about 170 psi ever since the engine was rebuilt. They did shave the head a bit to make sure it was perfectly flush. But like 60wag said if you are not getting any pinging then you really shouldn't worry about it.
 

3_puppies

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did you have the throttle open when turning over the engine?

as long as they are similar in value, I wouldn't worry to much
 
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Kyunggi, South Korea
Thank you guys,

To 60wag, nikos8/

Yes, there's no pinging sound and cylinder head hasn't ever been off.
My father was previous owner of my FJ62.
He and I did so many work for her but no experience of work for engine.
The only work concerned with engine was changing rear main seal when doing a clutch job.
I inspected pistons through spark plug hole following 60wag's advice but I saw there's very little carbon.
I suppose if built up carbon could effect compression, it might very thick and interfere with valve opening.

To 3_puppies/

I didn't pull choke(Mine have manual choke) it was fully opened and didn't push accel. pedal.
I leave as it is and did test.

To beaner, NocalFJ60/

The elevation of my town is somewhat less than 500ft.
But I don't know it could make effect to engine compression.....


And I omitted someting that my fj62 have very good fuel mileage about 19~23 mpg. Is it have any relation with high compression ?


Thank you,

Oh, Min Seok
 
Last edited:

roscoFJ73

 
 
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Jul 22, 2003
Messages
16,105
Location
Perth Western Australia
schaats said:
Hi,
I did engine compression check several times ago and got below result.

#1 : 175 psi
#2 : 176 psi
#3 : 180 psi
#4 : 182 psi
#5 : 176 psi
#6 : 177 psi

I saw FSM and found that normal compression value of 3F motor is 149 psi but mine is so high.
Here's my procedure.
1. Run engine to reach to normal operating temperature.
2. Remove all six spark plugs,
3. Connect compression guage to #1 spark plug hole.
4. Turning engine about three second.
5. Check value in compression guage.
6. Do 3 to 5 for the last cylinders.

I used reliable Japanese made brand new compression guage.
After checking, I checked again using with other compression guage and got same result.
I couldn't figure out why it's so high than commented value in FSM.
My FJ62 is 1988/06 and I haven't done any valve adjustment until now.
(My 3F motor's valve cover have no experience removing.)
Also this is first compression checking. So I don't have previous checking value.
Regarding mileage, odometer indicates about 140,000 Km, but my father drove 5 years without speedometer cable because of hardness of getting proper parts in South Korea.
So I guess that actual mileage is some more than 200,000 km.

Is there any people who could tell me whether it is normal value or not.

Oh, Min Seok
Schaats My mechanic in oz says they are the figures he looks for on a 3F carb engine warmed up.
Unfortunately mine didnt make the grade:mad:
I got something like 145 155 145 165 145 180
I too was confused after consulting my workshop manual but I think the difference is because the manual doesnt mention removing all the spark plugs at once.

Any way with those figures being so even, I would say you have another 300000klms to go:D
 
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While we're on the subject of compression tests. I just had mine done yesterday. I have a 1985 FJ60 from California.
100,100,100,95,95,100. He did them dry and wet and no difference so it's not rings right ? I know it's good that they are all close but it's very low isn't it? I don't have the FSM for 2F yet but my Haynes says they should be 150 +/- 30. What gives? pete
 

60wag

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If your lucky, the gauge was bad, or the throtltle was closed not allowing enough air to get sucked in the the cyls. More likely though, you neeed a valve job. When was the last time the valves were adjusted? Its worth adjusting the valves and redoing the the comp test before diving into a complete valve job.
 

treerootCO

Where are my keys?!
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NocalFJ60 said:
It would if he was 4,000 ft below sea level..The higher the altitude the lower the pressure or compression.

:bounce:

whew...I was worried about getting 60 on all my cylinders. :D
 
Joined
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Kyunggi, South Korea
Thank you guys,

to roscoFJ73/
My 3F FSM told me that remove all six spark plugs at once. So I did like that.
Thank you for your blessing :D

to Wherlwind/
If you did dry and wet check both and got same result, I think it means there might valve or head gasket problem.

to 60wag/
I'd gone to hardware store and checked my guage. but it's has no problem..
When was the last time the valves were adjusted ? It was 1988/06 in Toyota factory :D
I didn't do that until now :rolleyes:
Ok, I'll do valve adjustment. Thank you for your advice ;p
And, do you live in Boulder, CO ? I'd stayed in Colorado Springs until April 2005.
I also visit several time to Boulder and Fort collins. :)
Do you know good junkyard which have so many junk landcruisers at Salida, CO ?
Mrs. Nancy Wales who is the owner of Yotayard at Denver informed me that yard at Salida, Co and I'd visit there several times.
It was very interesting place to me.

Thank you again,

Oh, Min Seok
 
Last edited:
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San Francisco Bay Area
treerootCO said:
whew...I was worried about getting 60 on all my cylinders. :D

:doh:

That is alittle low for a 2f I would think.I would try another guage. That is good atleast if they all are within a few psi of the others. Good would be a 150 psi @ sea level so at like 5,000 ft the pressure should be around 125. I would look for around 120-130 psi in Denver for a good engine.

So at sea level the engine pulls in air at 14.7 psi and then by making the volume smaller in the cylinder by the piston moving up compresses it to 150 psi. If the valves are not closed all the way you loose some air form the cylinder while the piston is moving up. Most people probably know this but thought I would describe it since we are all learning.
 

treerootCO

Where are my keys?!
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My tired engine runs great....you just have to wrap it above 5,000 and she perks right up :D

**don't try this at home kids, redline is 3800 to 4000 ;) **
 
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Messages
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Sth Australia
Thank you guys,

To 60wag, nikos8/

Yes, there's no pinging sound and cylinder head hasn't ever been off.
My father was previous owner of my FJ62.
He and I did so many work for her but no experience of work for engine.
The only work concerned with engine was changing rear main seal when doing a clutch job.
I inspected pistons through spark plug hole following 60wag's advice but I saw there's very little carbon.
I suppose if built up carbon could effect compression, it might very thick and interfere with valve opening.

To 3_puppies/

I didn't pull choke(Mine have manual choke) it was fully opened and didn't push accel. pedal.
I leave as it is and did test.

To beaner, NocalFJ60/

The elevation of my town is somewhat less than 500ft.
But I don't know it could make effect to engine compression.....


And I omitted someting that my fj62 have very good fuel mileage about 19~23 mpg. Is it have any relation with high compression ?


Thank you,

Oh, Min Seok
I'm a bit confused. I thought for chocke to be fully open. U have to fully pull choke out?
And for throttle to be open. U have accelerator flat to floor?
Did I do my Comp test wrong?
 

Kleatus

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Schatts, your numbers are about the same as those of my '89 3FE that has had about 0.88mm milled off the head and a fresh valve job.
 
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down in a hole.
Matty F, you pull the choke to CLOSE it; and the gas pedal should be on the floor for a compression test...I recommend adjusting the valves FIRST, then cycle each cylinder 3 times at about 3-5 revs of the starter using the same revs per test per cylinder. having a hot engine with open plug holes and a wide open throttle will help get the numbers up, but even if done cold with a closed throttle, as long as each cylinder is tested consistently, you shoud get usable results. ie are the numbers high enough and are they within the correct window across the board...HTH
 
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Matty F, you pull the choke to CLOSE it; and the gas pedal should be on the floor for a compression test...I recommend adjusting the valves FIRST,.HTH
I adjusted valves hot? Pedal flat to floor but pulled choke out. But that must not have affected numbers too much as they were still high. A tad uneven
1 170
2 165
3 171
4 165
5 170
6 179
But am losing coolant and a bit of it too. with no visible external leak that I can see and so far pressure test came up fine. Gas test when hot came up negative. And can't see any contamination of oil. So I'm not sure but would assume there's only one other place coolant could be going and that's out the exhaust.
 
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