My no start issue, LOW COMPRESSION!!!!!! New diagnosis!!!!!!

[Doug]

Idling your engine to break in rings is a fallacy. Drive it hard is the best way. Those rings need cylinder pressure to drive them hard against the bores to assist them in conforming to the bore eccentricity. You have a limited time to do this until the honing scores wear smooth. At that point the process will slow to almost nothing. Don't baby it! Unless you like to tear down engines to replace previous good work and parts!

[ORCoaster]

I totally agree, you don't need to drive it like you stole it but you need to vary it up an down more than usual.  Use the engine for a brake and rev it up a bit longer than you would normally.  Search the threads here.  At one time we had this discussion.  How to properly break in a new engine. 

[R.O.R-2.0]

when i break them in, i run them like i stole them once they are up to temp..

im a firm supporter of the "run it like ya stole it" group..

makes the rings seat ALOT faster..

[theman53]

I totally agree, you don't need to drive it like you stole it but you need to vary it up an down more than usual.  Use the engine for a brake and rev it up a bit longer than you would normally.  Search the threads here.  At one time we had this discussion.  How to properly break in a new engine. 

x2. Run it hard, but don't run it fast...don't mash it and hold it to the floor, but use all of the rpm range.

[rabbitman]

Yeah I only drove it for 15 minutes and I varied the rpm a lot, engine braked a lot and floored it a lot. Whenever I ran 3500-4000 rpm I'd let it engine brake back down and go easy on it for a bit to let things cool.

It's cold out now so I might have to wait a little while to hit it again.

[R.O.R-2.0]

I totally agree, you don't need to drive it like you stole it but you need to vary it up an down more than usual.  Use the engine for a brake and rev it up a bit longer than you would normally.  Search the threads here.  At one time we had this discussion.  How to properly break in a new engine. 

x2. Run it hard, but don't run it fast...don't mash it and hold it to the floor, but use all of the rpm range.

yea, i guess i should have clarified..

like Lucas said, dont just go out and red line it.. vary the RPMs, but load the engine as much as you can.

i would keep it under 5000 for a while, or if you do see 5000, just do it briefly, then shift..

[rabbitman]

I've never hit 5000 with either of my diesels. My rabbit just doesn't sound smooth, it might just be the whole body vibrating though. 4800 is my max with it.

The golf feels much smoother and I've hit 4500 a few times before the re-ring.

[rabbitman]

So the other day I tried starting the golf at 15F without plugging in, it cranked fast and long and finally started but quit when(I assume) the GP's shut off. I glowed again and it cranked the same and just before it should've started it just totally gave up and sounded like 3 dead cylinders and one firing. rarararRARrarararRARrar......and so on.

Is in possible for the hydro lifters to hold valves open?   I saw a 1.9 TDI do it once, they would crank it (without firing at all, the brain wouldn't turn the fuel on) and suddenly it would sound like it was cranking with the injectors removed. Wait a bit, try again and it would repeat the same.

Mine doesn't sound like zero compression though.

[rabbitman]

So yesterday I drove about 210 miles and all was good, I haven't checked oil comsumption yet.

Every now and then it would give a tiny little jerk like it was missing for a split second but it was hard to tell it apart from the tar lines.

Engine is quiet and very non-intrusive until 2800-2900rpm and higher then it takes on a hum that drones constantly.........

This morning it was plugged in for 6 hours and started with a little more cranking than I like, maybe 3 seconds. It wouldn't seem so bad accept for the starter groan that I'm sure slows it down some. I'll have to tear into it and change some bushings maybe.

Also since it was outside the interior was cold so the speedo was a little noisy, if it doesn't get worse I can live with it but otherwise I hate the little rattly/ticking noises.

The ride is very luxurious compared to my rabbit but it's not nearly as firm and sporty. It doesn't go "BANGBANG" on every tar line.

The seat is not made for my back and the floor is cold (my feet never got comfortably warm) so I'm gonna put some insulating foam under the carpet.

[rabbitman]

So I feel as one who failed at diagnosis..........

My rings are good but for some reason MY VALVES ARE BEING HELD OPEN.......I have yet to determine if the valve stems are too long or if the lifters are not bleeding down right.........

I did account for valve length when I ground the seats, the bentley has a spec for tip of stem to vc surface and IIRC I had to shorten all of the valves.

[smutts]

Valves held open? If the oil pressure is very high this can happen with hydraulic tappets, but this usually happens at high revs with a stuck oil pressure relief valve. High speed misfire that will drive you mad looking for it.
BUT if it is at startup, oil pressure is zilch, so look for something else.

Over lapping or cutting the valve seats, if the sealing area where the valve meets the seat is too broad, that can cause compression loss.

Somebody put valves that are too long, valve seats too deeply recessed, cam with too large a base circle radius er............. , you have your work cut out eyeballing that head.

My doubts with the lifters not bleeding down, try a very thin feeler guage between the heel of the cam and tappet when cold from overnight, good luck.

[rabbitman]

I depressed a valve, stuck a .0015 feeler gauge in and couldn't pull it out. Not sure if the lifter was totally collapsed though.

The cam is a Dr. Diesel performance grind, I would think that would give it a smaller base circle and have less chance of holding valves open....

I still need to measure the stem to VC surface to know if they're out of spec.

[rabbitman]

So I just went out, washed a lifter out with gas by pushing/pulling on the moveable part, put that one lifter into each lifter bore in the head (the head is installed) and put the cam in, the cam actually rocks on the lifter.

If I push hard enough to seat the cam on its journals the valve will open a very easy-to-see amount. I don't know why this engine ever ran........

I also took a VC surface to valve stem measurement and it was .010" shorter than spec. Not sure why I missed that since I remember thinking about but it would appear I need to pull the head and redo some things.

If the valve doesn't have enough left to grind off the stem I'll be looking for new seats or another head that hasn't had the seats ground yet.

[rabbitman]

Also, on the off chance that I have the wrong lifters, if one of you has a lifter laying around could you make sure it's flattened and measure the distance from the cam surface to the moveable part that touches the valve stem?

Mine measures .778"

TIA

[theman53]

I have one here that is collapsed on my computer table and it is real close to 1/2", no where near 3/4