2F Compression (1 Viewer)

[NMC_EXP]

To start, yes I ran a search for 2F compression and came up with an empty sack. Therefore all you who are so inclined can back the hell off.

Questions:

(1) For a 2F what is factory new/good rebuild compression?

(2) My 2F engine with 140K miles has 110 to 115 PSI compression.

(3) At what compression should you consider a valve job, head rebuild?

Thanks

Jim

 

[OlYellr]

To start, yes I ran a search for 2F compression and came up with an empty sack. Therefore all you who are so inclined can back the hell off.

Questions:

(1) For a 2F what is factory new/good rebuild compression?

(2) My 2F engine with 140K miles has 110 to 115 PSI compression.

(3) At what compression should you consider a valve job, head rebuild?

Thanks

Jim

You want to see even compression inall cylinders. No variance greater than about 10% (14 psi).

I believe the FSM on 2f says 114 and below is out of spec and new is 149. My opinion, 120 and Lower is a tired engine.

 

[NMC_EXP]

You want to see even compression inall cylinders. No variance greater than about 10% (14 psi).

I believe the FSM on 2f says 114 and below is out of spec and new is 149. My opinion, 120 and Lower is a tired engine.

View attachment 3106144

View attachment 3106145

Thank you kindly.

 

[2mbb]

The number is somewhat subjective. What is more important is how even the numbers are across the cylinders.

How accurate is your compression gauge? How strong is your battery? Did you remove all the spark plugs? Are the valves correctly adjusted? Did you fully open the throttle? Is the engine warm? How many engine revolutions to get the reading?

What did Mr Toyota do to come up with the spec?

 

[NMC_EXP]

The number is somewhat subjective. What is more important is how even the numbers are across the cylinders.

How accurate is your compression gauge? How strong is your battery? Did you remove all the spark plugs? Are the valves correctly adjusted? Did you fully open the throttle? Is the engine warm? How many engine revolutions to get the reading?

What did Mr Toyota do to come up with the spec?

All good questions.

#1, how can I determine how accurate the gage is? I was an engineer with Caterpillar for 30 years. There was a gage lab to which we would send our gadgets to have their accuracy confirmed, traceable back to NIST standards.

To answer your question I do not have the faintest idea of how well calibrated that compression gage was. When was the last time you ran a compression check on your engine did you get the gage certified back to NIST compliance? Rhetorical question of course. You and I did not.

I do not know where to go with this.

Oh well.

 

[OlYellr]

When was the last time you ran a compression check on your engine did you get the gage certified back to NIST compliance? Rhetorical question of course. You and I did not.

I do not know where to go with this.

You do the best you can, until you know better.

For me and my compression test, I used one I bought AND I borrowed one of a different brand. Came out basically the same. (Being a fellow engineer, naturally you can’t statistically do a average of 2 - but good enough for my decision making requirements)

I bit the bullet and on the final stages of a complete rebuild and glad I did and will enjoy the rig for many years to come.

 

[2mbb]

Sorry my response was not helpful. My point is that if you want to compare your numbers against others you need to make sure both parties are doing the testing the same way. There are several factors that can effect the result. It is more likely your cylinder to cylinder numbers are comparable . I personally would not assume your 145k engine is bad because all the cylinders have low compression measurements. It is unlikely they would all wear out that much that quickly.

And, you are correct. I have never calibrated the gauge on my compression tester--which was originally purchased by my father in the 1970's. But I have used it on my vehicles through several tests through the years. Below are some numbers from my FJ60/2F. to me they all seem high, so my gauge may not be accurate. But the numbers are consistent across the cylinders (more or less) and through the years.

If you are really worried about your compression, then get a second opinion (another compression tester, cylinder leak down test, etc.) before you take on removing the head.

PS. It looks like I'm due for another test soon. I think I've put on another 25K miles.

 

[OlYellr]

Sorry my response was not helpful. My point is that if you want to compare your numbers against others you need to make sure both parties are doing the testing the same way. There are several factors that can effect the result. It is more likely your cylinder to cylinder numbers are comparable . I personally would not assume your 145k engine is bad because all the cylinders have low compression. It is unlikely they would all wear out that much that quickly.

I would agree.

Mine were not even. Not even in the 14 psi of each other range. My decision was easy. My wallet got the harder task.

If all mine were say around 110-115, I would keep on driving for a few years then reevaluate if then would be the time- for me I want a DD and then some along with the peace of mind as I never intend to sell. Point is the wants and needs of your rig factor too on what you want and when.

And don’t look for a problem if there isnt one. There are plenty of legit issues on these things as is.

Run the compression tests, see what you got.

 

[SteveH]

(2) My 2F engine with 140K miles has 110 to 115 PSI compression.

What is your elevation? Those are perfectly good numbers at my 7000' elevation.

I bought a 2F that had 17K miles on it (it has been stored for many years, and this was in 1991) and all the cylinders were at 119-120 at 7000' elevation. The engine was 'like new' at that point.

 

[NMC_EXP]

You do the best you can, until you know better.

For me and my compression test, I used one I bought AND I borrowed one of a different brand. Came out basically the same. (Being a fellow engineer, naturally you can’t statistically do a average of 2 - but good enough for my decision making requirements)

I bit the bullet and on the final stages of a complete rebuild and glad I did and will enjoy the rig for many years to come.

Spoken like a true engineer....I mean that with gratitude. No BS.

Being a "civilian" for years now without the technical backup of a Fortune 100 corp., I truly miss having the opportunity to get my personal gages and gagets checked out for accuracy/precision/reliability. Violation of company policy but you could get it done.

After getting burned a few times early in my career, I got real paranoid about whether or not your measuring device was telling the truth.

*After all that, a question*....does anyone sell a rebuilt head ready to drop in and bolt on? For sure my valve stem seals are shot in addition to low compression.

I'm on the downhill slide and I would not be doing that sort of thing myself. About all I can do anymore is drive it.