This is one of those educational posts.

As some of you know a month or so ago i blew up yet another type r engine. compression read 160-160-90-160

sounds like a tired R motor with a cracked piston doesn't it?

have another jdm R motor show up the other day and compression test it on the floor cold. hovered between 140 and 150psi. floored i just couldn't figure it out..this jdm motor had tan exhaust valves and zero carbon on the seats. i double check cam timing since that can effect compression. nope, it's dead on.

i get another compression gauge, engine has 230+psi cold. not only that but it took all of 2 cranks to get it

had i known this i would have tossed another piston in the first motor and ran it. i figured it was a tired motor and needed to be rebuilt. an itr with 160lbs is really low right?

moral of the story is don't bet the farm on a harbor freight compression gauge.

my 160lb itr engine was probably 220ish minus the one cylinder i could have tossed an oe piston in and fixed

 

160psi on a b18b1 is LOW lol i get 170 165 185 190 on mine and its ****in tired

 

^ Why are you laughing so hard? He said it was a Type R motor.

 

damn. shoulda done a leakdown, bud.
or invested in a higher caliber tool. compression tester is pretty critical.
but oh well. no use cryin over spilled milk. take it as a lesson learned i guess

 

because its supposed to be 250 or better on a type-r

 

racebum did you buy a new gauge? curious which brand you went with im about ready to toss my dads early 1980s compression tester as I also think it doesnt give accurate results at all

 

My H-F tester reads low as well. But it's precise.

 

hmm, interesting. I am wondering how mine is preforming

 

KD tools has always been known for a quality product and their compression testers are under 40. i bought a mint used one from a big time tool reseller for 20 shipped last night. the gauge pictured is a actron and it seems to be accurate too. that engine you see having 240lbs cold on the floor read 100lbs less with the POS gauge

i also believe those tube screw in adapters effect the numbers. you're going to be most accurate just screwing the hose in the cylinder. the tube we tried on this gauge dropped the readings as well

 

Good information to know. Sorry you had to find out the hard way

 

don't think i'd classify KD as an exceptionally high quality brand, though better than HF for sure

 

KD is part of the dahner tool group, it's what, gearwrench level, above craftsman but below matco?

least that's where i would place it.

a new snap on gauge is 89

http://buy1.snapon.com/catalog/item....re&dir=catalog

and another 40 for the hose

http://buy1.snapon.com/catalog/tools...e=snapon-store

that's 120 plus shipping. the KD tools tester

is 35 shipped

http://www.amazon.com/KD-Tools-KDT24...sr=1-1-catcorr

and is available special order at sears.

one of those things. i have a snap on flex ratchet that's 3x the cost of a gearwrench. personal call on if you want to spend the same on a compression gauge. i will say that i've never had any bad experience with KD or gearwrench for mid level tools

 

Damn dude, I feel for you.

Just goes to show, for tools like that, there is no replacement for Snap-on/Mac/Matco

 

personally i'm always keeping two on hand from different brands after this. if something seems suspect try the other one. it's unlikely two will fail to the same degree

also hate the metal tube extensions. tested another one today and it f'ked the numbers. i highly suggest just going hose to spark plug hole.

could be the reason snap on does not sell metal tube extensions.

from what i can tell the tubes hold too much air and reduce air pressure at the gauge. think of a pump in a small chamber. it will create more pressure than the same pump in a larger chamber.

tried a metal tube with actron gauge on the pictured R engine you see on my shop floor. every cylinder read 140psi, without the tube it's the 240-245psi you see pictured

 

Sucks man - sorry to hear you had to learn the hard way

Correct me if I'm wrong though, I always thought that compression test readings were more of a "relative" measure. As in, compare the readings of the same tool between different cylinders rather than looking at the "actual PSI" reading. So if 3 cylinders show 160 and 1 shows 90, then compression test says "problem in that 1 cylinder." (as opposed to saying "need to improve compression by x amount of PSI"). Curious to hear your thoughts, thanks

 

you're right

BUT

compression numbers are also how you can gauge the life of an engine. when you start getting leakage in the valves and in the bottom end numbers gradually go down over time.

in the case of my last R engine, that one cylinder did have a cracked ringland or mangled rings. but, i assumed the other 3 were down from mileage and track use. 160 is basically the end of the life for an R engine. oil burning also gives some clue but with a cracked ringland i was eating a quart every 200-300 miles. i considered a rebuild but thought, ****, how much hell has the head seen? anyway, had i gotten 220lbs which is what an accurate gauge would have shown based on the differences i tested, 220 isn't down that much from stock on an R and still has some life to go. 250 is basically like new on these engines which you'll either see warm or cold with a few drops of oil

had a realized it really was just one cylinder i would have bought a 75 dollar oe jdm itr piston, ran the ball hone, bolted it in and drove. rather than part it and buy another jdm R engine

side note: i really need to buy a leakdown tester

found a couple

http://www.ebay.com/itm/Total-Seal-1...ht_1884wt_1163

which looks to be a good one, total seal is a ring manf

or, the generic brand

http://www.ebay.com/itm/JEGS-Perform...#ht_1730wt_905

 

i'd assume snap on offers lifetime calibration testing and replacement though.
not sure on the kd

 

Damn, that's crazy how much of a drop there was just because of the metal extension.

 

tell me about it

and im sure different models do different things

i just wanted to put all this out there so people can burn this information to memory and if they are caught in a situation, recall what they read and try a different gauge or loose the tube when they do a compression check

 

You are correct. Different gauges may read differently, that's why the general rule of thumb is you don't want more than 10% variance between cylinders.

Racebum, did you take the head off and inspect the first motor? Would have seen the other pistons were fine, could have just re-ring'd it, changed the cracked piston, and been on your merry way. Sucks that the gauge caused so much headache though

 

How many miles did your "tired" ITR engine have on it?

 

Thanks for the heads up Note taken: If comp. test readings are low, try another gauge.

 

i'm still mad as **** about this

that's exactly what i would have done. there was only a 5lb difference between the healthy cylinders

 

172,000kms

i got the cluster out of the car it was pulled from, came with 68,000

engine still had a lot of life left with work i had the skillset to complete, total screw up on my part

just wanted to share so no one else makes the same mistake

 

What'd u do with the old motor? Why not rebuild it and have a spare...or sell it?