I picked up a 84 GL yesterday and have been working on it today fixing it up and such for a cheaper daily driver but I checked the compression and the first three cylinders were all about 90 and about 75 on cylinder 4. The guy i bought it from said the motor was replaced with a used low milage one. The motor has solid lifters (which need adjusting) and not the hyro's, so i know it was replaced but i have no idea to the mileage on the motor.

 

How can i tell if it just needs a valve job? and how much would that typically cost ? should i sell it?

 

any advice is appreciated.

I am questioning your test results and test procedure - those are REALLY low numbers. EA81's in good condition should push around 150 to 175 psi compression. I have one that pushed 220 psi last time I checked it.

 

What's your test procedure? Those numbers are on the low-end of what should even run at all - let alone hold a proper idle.

 

GD

I took my readings while it was warm with all of the plugs out and at least3 compression strokes on each cyl.

 

On a scale from 1-10 it runs like a 6. It doesn't stall or anything but it definitely needs some help. the motor seems like its a little off balance at about 1k but it does idle decently with the exception of the valves being out of adjustment.

Might want to try it again with jumper cables from another battery to give it some more juice and prop.....hmm, i'm not familiar with carbs, but prop the throttle plate open (would be throttle plate in an FI car) so it has unrestricted air flow.

 

GD (or others) is there any chance that since this motor was swapped it's actually a turbo block, I know EA81T's are rare but what would the compression be on those?

 

Valve job isn't that big of a deal, but not knowing anything about the car/engine you really don't know if it's the rings rather than the heads, even though heads are most likely. A leak down test can show where the loss is happening.

 

If you only needed headgaskets then you wouldn't necessarily need a full on valve job, but it's a pretty smart thing to do while yo'ure in there, I almost always do. To mill both heads and do a valve job and basic parts (head gaskets, valve stem seals, intake/exhaust manifold) you're talking roughly $200 (more if you're in a high dollar urban area which may have high machine shop prices). DC market = very expensive. Rural WV = insanely cheap.

 

Personally if it runs and you want a cheap DD without dumping tons of money into it I recommend driving it for a while before deciding. It's no fun doing a head gasket job only to find out it has transmission issues or all sorts of other problems you don't want to/can't afford to contend with. After a month you'll have a better clue what kind of money you want to put into this particular job. If it's in great shape you might decide to go all out, if not you might cut some corners.

Edited December 1, 200916 yr by grossgary

At the very least,along with all the plugs out,you need to have the throttle wide open. Otherwise,your engine can't suck air thru the intake which will give low readings. Ideally,you'll get the carb in the WOT position without letting fuel into the intake. When your cylinders are awash with fuel,you can get a false high reading.

Yes - disconnect the fuel pump, run it till it stops and then crank till it's not trying to start anymore - pump the throttle to expel fuel from the accelerator pump. Fuel being pulled into the cylinder can wash down the oil from the rings.

 

You test it with the throttle wide open (choke pulled off), all plugs out. Then start cranking - it should come up to it's max reading in about 5 compressions strokes - which is about 20 revolutions (4 stroke engine - only one in 4 is a comp. stroke).

 

If you see any wide variation after doing that, then you need to do a leak-down test on each cylinder to determine the reason for it. I like to roll the engine over on the comp. stroke as I'm doing the leak-down to see if there are any bad spots in the cylinder as well as listening for intake and exhaust valve's not seating.

 

EA81T's will have lower comp. numbers but still not typically that low. Around 120 psi or so give or take. They are also hydro lifter engines so it's probably not a T block.

 

Valve adjust takes like 15 minutes - get that done - it's easy.

 

GD

should i sell it?

any advice is appreciated.

 

YES.... SELL IT TOOOOO MEEEEEE!!!!!!!

 

Not sure where Warren is but I would buy that car right now... sight un-seen for what you paid for it. (but my account says different.)

 

First, you probably did compression test wrong.

 

Does it need a valve job... probably not..but?

Yea... agree shouldn't run motor with bad valve but a cheap fix is too turn up the radio and put another 100,000 mile on the motor.

 

If you want a cheap runner I think you have one, bond with it. Check the usuall, plugs, wires, rotor, cap, check for vacuum leaks, loose oil cap, and I like to run "Seafoam" engine cleaner through them when I pick one up.

 

The EA-81 engine is bullet proof little unit, trust it.

 

I get the impression you are new to the EA-81 motor??... The valve adjustments don't take too long but a bit more then 10 min. for me:-p

You will need new valve cover gaskets, if they are cork coat them in automotive-Grey RTV (got idea from GeneralDisorder) let them dry over night and then take covers off and adjust, put back together...the valve cover bolts are like 12 inch torque or something like that... not much.

 

I have two 84's, my favorite year!

Edited December 1, 200916 yr by Indrid cold

OK, I ran another test on it today and i got considerably higher readings. i just pulled the fuel pump fuse and and propped the throttle wide open AND hooked up the battery charger on low and I got 140 in all of them but #4 if (i remember right), it read 120...

that sounds more like it.

 

sounds like you got problems. specifications are that it should be within 10-15 percent variation i think? you're close, sounds like you have problems or will soon.

I bought an 84 Hatch 2 years ago, it could have perfect compression or it could be a mess in there... I didn't test it.... didn't care too and wouldn't make a difference to me if it was 5% or 20% off, it runs, it will continue to run and when it doesn't I will get on this board and track me down another engine. Should it get to where the valve is compromising performance to the point it becomes obvious .. then.. o.k, I would do valves, or find another engine or subaru.... last one I got was cheaper then doing valves...

 

my .02cents

Edited December 3, 200916 yr by Indrid cold

good point it could run a long time like this without ever really getting worse, my bad. i kind of assumed you were tracking down a major issue of some sort though - not often folks do compression tests for small reasons.

Well Gary - I run comp. and leak-down tests on all my rigs when I get them. It doesn't stop me from buying them - I just want to know in case I notice the running conditions change later, to tell overall condition, and to thumbnail gauge what I might expect from the engine for the future......

 

My '83 hatch that I've been driving pretty much daily for the last two years has 240k on the motor. Compression test results were:

 

1: 165 psi

2: 135 psi

3: 160 psi

4: 165 psi

 

That low cylinder doesn't affect it much. The gas mileage is the worst effect as far as I can tell - I'm around 26 MPG with my lead foot. But around 32 on the freeway. It could be 1 or 2 MPG better without that low cylinder I'm sure.

 

Can't tell by the way she runs though. Purrs along like a kitten at 700 RPM with a DGV-5A Weber. Enough power to chirp them into 2nd.

 

GD

Edited December 3, 200916 yr by GeneralDisorder

gotcha, i didn't think compression tests were that common but i can definitely see the value in it.

What pressure should I be reading for an EA71?

What pressure should I be reading for an EA71?

 

Should be the same as for an EA81 if the compression ratio is the same. Compression ratio, not engine size, dictates what the numbers should be. But as long as they are over 100 psi it really doesn't matter what the actual numbers are - there are so many variations due to testing procedure, aparatus and environmental conditions that you can't effectively compare numbers. Each test should be veiwed as a unique entity - the only thing you are looking for is that the cylinders are within 10 to 15% of *each other*. The numbers should be somewhere north of 100 psi but that's about all I or anyone that knows anything about the inner workings of a compression test should be telling you.

 

GD

I don't know what the number is for these motors. Camshafts affect the numbers you see, but that's fixed unless you change it.

 

Normally asperated, well, you take the cam that gives you the highest compressing numbers. Different opening/closing rates, center lines...so on and so forth.

 

Edit: Chilton doesn't give the number for the earlier EA's that I can see. A 9.0 Carbureted EA-82 , the number is 161lbs@350 rpm. A SPFI is 168psi, due to the .5 higher compression ratio, probably.

Edited December 3, 200916 yr by Quidam

Did you check plugs??any wet plug on the low cylinder?..x-ray eyes would help us all..I bought 84 gl wagon 4x4 ea81. Love those wagons ..

Over ten years since last post, three since quidam signed in

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