low compression
 

my 1.7 w/ carbs is missing...no, I know WHERE it is, but it's running rough!

My dad suggested doing a compression test and here's the results:
cyl. 1 - 130
cyl. 2 - 140
cyl. 3 - 90(:eek: )
cyl. 4 - 65-80 (:eek: :eek: ) (and with the compression tester in instead of the sparkplug, the car sounds the same as if it wdid have the plug in!)

ok, so...
1) what is the first thing I should do?
2) if I get the valves done... do I need to do the rings as well? should both be done to be sure?
3) should all 4 be done?
4) could this be anything besides the valves and/or the rings?

:(

I've had good experience with just working on the head, and leaving the rings alone. It's definatly not the way to do it for longevity, but it's a darn good bandaid.
You can check where your cylinders are leaking by getting a connector that will screw into the spark plug hole on one end and a quick disconnect for your air compressor on the other. Make sure this hose doesn't have a check valve in it. The one for my compression tester looks like it would work, but it have a one-way check valve inside. Now, place the cylinder to be tested at TDC of the compression stroke and plug in the compressed air. It might take a few tries to get at TDC, if you're off a bit the piston will be pushed back down into the bore. Use about 90-120 PSI and listen at your intake, your exhaust pipe, or your oil filler. Whichever one you hear the air at is the one that's leaking.
If you've only got valve problems, just do those.

Split the case, and do it right....Valve jobs just don't work these days, everything is worn.

Try adjusting the valves. Always try the cheap and easy things first...

--DD

I adjusted the valves recently(about a month ago) and changed the plugs at the same time... which made things a lot smoother, esp. when the engine gets warm!! the valves were't far from right to begin with. so I thought it might be electrical or the carbs since it runs very good once the engine gets warmed up...

but the compression test debunks that for the most part...

I will hook up a compressor and try to find the culprit.. i need a bandaid for a while before I can afford to do the right thing... with any luck I'll be able to get one of your RAT kits Jake! :D but right now I would like to just "get by" for a while.

I really appreciate everyone's responses.

one more thing... and this is a stupid question I'm sure, but... do I have to pull the engine if it's just the valve/head on that side? b/c if I do have to pull the engine, I may go ahead and do the rings too... everything except split the case.

Toss a little oil down the spark plug hole. If the compression comes up, it's rings. Stays the same, most likely valves.

BTW....do the check when the engine is warm.

Depending on the mileage, Type IVs are best totally rebuilt. Especially if over 100K miles....

I'd caution you on using the compressed air to do a leak down test. When you are a bit before or after TDC, 100 psi air will push that piston with considerable force. I assume your engine is still in your car. You can leave it in gear and set the brake or chock a wheel or something.
I had mine on a test stand doing leak down tests and had some trouble getting the engine locked. Don't think you can grab the fan and stop it! Don't stick screwdrivers in the fan blades! I ended up taking the starter motor off and making a piece that bolted in and engaged the teeth on the flywheel.
On another note, and this is not a recomendation just what happened to me, I replaced my rings over a year ago. I was suffering from low compression and burning oil. All I did was clean all the carbon out of the heads, I didn't even grind the valves. I thoroughly cleaned the ring grooves of carbon buildup and put rings in it. I lapped the cylinders into the heads. I honed the cylinders by hand. Last time I checked compression was running 130-135 on all four, as I recall.
On the other hand, I took this shortcut to " buy some time". Having taken the shortcut, the tendency is to get the most out of that time, not actually prepare for a proper rebuild.

I guess you could do the head with engine in the car. It is not a big job to pull the motor, though. What you lose pulling the motor and putting it back you will probably more than make up in easing the engine work

The only way to pull a cylinder head with the engine in the car is to drop the engine halfway out. The head will not fit around the trailing arm or suspension console ears, so you have to lower it out far enough to clear that. Once you've gotten that far, it's not much more work to just drop it the rest of the way. And access to everything will be an awful lot easier.

--DD

ok, thanks for the info everyone...
I will...
1) test the compression with the car warm... if the compression is fine warm, is this anything to worry about? or does will that point more towards the valves? if the compression is still low... what would that suggest the problem is.
1.5) I also plan to re-adjust the valves on that side to see if I may have gotten them too tight... just to rule that out. since this was my first valve adjustment....
2) if the valves are the culprit I will probably just do them for now and wait on a rebuild until the non-driving season (most call it winter, but in Tx, it's just the rainy time) and then rebuild it... do you think this is a safe thing to do, or am I risking creating a problem that will cost more than a rebuild to fix.

I only drive the car 2-3 days a week, mostly to work and back (<10 miles one way) and don't have the time/money to invest in a full rebuild right now. but I would like to bandaid it to last until "winter". do you think that will be ok?

There is always a risk--there is a risk to rebuilding the whole engine, to doing nothing, or to just doing the valves. Worst case, your tight new "top end" could stress the "bottom end" to where a rod fails, banging around in the crankcase at high speeds and putting holes in everything. Best case: It drives fine.

Jake hates the "top-end only" deal; I am more ambivalent. I have seen that very often a "temporary fix" like this has a way of becoming permanent, until something big happens... "Oh, that'll hold for another few months, right?"

"Winter"--
High temp drops below 65F, and liquid water falls from the sky. Sounds like winter to me!! :D

--DD (who is very very glad to be out of the midwestern winters he grew up with)

yeah, I understand Jake's concern... esp w/ doing only the heads b/c that will put more stress on the rings which probably need to be replaced anyway... :(

so, I think I will drive it for a while until I get enough time and money to do the rings and heads all at once... if that causes the crank/rods to fail... I'll have to get with Jake about a new longblock! but since I don't drive over 70-80 ever(no place to get up that fast in Big D without cops everywhere) and I don't put that many miles on it... hopefully the top-end rebuild will last until next spring at minimum and I will have more time/money/space(I don't have a garage right now either) and I can do it right... or I may get lucky and find a 2.0 cheap enough to rebuild it (slowly, while still driving the 1.7) in the interim

does anyone know a good (north) Dallas shop to do the heads? Wes at H&H recommends Knight's VW in Garland... and I tend to trust both places since I've dealt with both on stuff before... but I was hoping to get a customer's opinion who had this done here in Dallas... or maybe another recommendation.

Yeah, I call a valve job a "Patch up" and they just don't work anymore..

Jake only does complete engine, not longblocks, too risky...I wanna be the man that buttons the entire thing up, fires it up, and gives it hell on the dyno1

well, Jake...

If I could, I would!!! I'm a believer brother! the dynos and testimonials from here and shoptalk forums don't lie. unforunately, those sweet-ass 2270 t4s don't grow on trees... if they do, you have a helluva green thumb! :P

right now, I just can't afford the fruits of your labor. so, until I can... rings and valves will have to do... now, if I get in there and the piston is bad too... I will have to figure something else out, maybe a 2.0 off ebay to patch things for a while... but with the wedding coming up, I just can't afford to buy a nice 2270 yet :(