#3 Cylinder Issue Returns :-(

Good news and bad news.
I drove about 45 miles up into the foothills this morning and when I got there, my #3 cylinder problem had returned. Same thing, rough running and no difference when I pull the #3 plug wire. I got it home and decided that even though it made no sense that my Compu-Fire breakerless ignition would be lighting up 1, 2, and 4, but not 3 I would replace it with a Petronix module. As I expected, it made zero difference, but my tach (the 4th one) has also been acting up lately and the good news is that its working now! Go figure.

I also tried using some SeaFoam in the gas and the crankcase, but it did nothing for my #3 cylinder problem. So, I'll be returning it to my mechanic on Monday morning and I expect he will be removing the head this time.

I have to get this thing fixed, so I can drive it up to Tahoe before the rainy season starts.
Troy

I've been thru this with many just bought beaters hoping for a miracle, most recently a 2.0l 914 that PO said was running well.I took it out and found the inevitable loose valve seat(didn't have leak down stuff or time).
Sorry Troy, it'll pass and the mystery will be over.
Not that your beautiful car is a beater!!

what does the plug in #3 lok like, if its black it wont fire, you can use a timing light on each wire to see if their firing. bill

Thanks Bill. We have already been through all of that. The plugs and wires were one of the first things that were replaced. The spark is fine. It is definately, a valve problem.

I'm considering pulling the engine myself and having the heads redone. What should I expect to pay to have the heads rebuilt? Are there different types of springs, valves and valve seats that I should consider asking for or do I just tell them to fix it?

Also, I would prefer to not get any further into the engine than just removing the heads, but is there anything else I should do while the engine is out and the heads are off?

Thanks for the help.

Smart to pull it before valve breaks or seat damages piston.

I'd look at new heads - big improvements in new ones. Double valve springs mean higher RPS, long threads for plugs and smaller spark plugs mean less chance of cracks in head. This is a job you can do yourself if you can pull the engine. Just need to borrow a torque wrench.

$500 or so new - old might be worth $100


http://www.cbperformance.com/catalog.asp?ProductID=1803

Too bad you aren't closer to Ontario, I could do a leak down test to determine if it's valves or rings. I don't remember but do you have twin Webers or Deloroto's?? If so, the most obvious and easiest thing to do is to clean out the idle jet and see what happens.

In regards to heads. I don't know what kind of a budget you're working with but ported and polished heads make a huge difference on a VW engine. I'm not an advocate of double valve springs or heavy duty springs unless you're consistently revving over 5,500 RPM's. A matched set of stock valve springs makes your cam, followers and rocker arms last longer. If you don't have solid rocker shafts (no wavy washers) then have them spaced out by someone who knows what they are doing. It prevents those funky clips from coming loose and destroying your engine. It's a relatively cheap fix as the kit has solid spacers that your insert on the rocker shaft between the rockers. About .005 between each spacer is fine.

If you remove the heads then why not change the barrels and pistons. It can be done very easily without splitting the engine case and doesn't cost much. If your engine is stroked beyond 76 mm's use "B" pistons otherwise use "A" pistons. If you have spacer beneath your pistons then save them and, if you decide to buy new heads, have your old heads cc'd to determine their volume. Try to buy heads with the same cc's to maintain your compression ratio. If you can't I can figure up what spacers you need if you give my the deck height (distance between the top of the piston and the top of the barrel at TDC)

Troy before you pull the motor out have your mechanic do a leak down on the motor that will tell you what's going on in that cylinder if it has a bad valve or rings

CB is right up the road from u, if u arent in a hurry and have some extra $ Pat can do u a 2110 in proper fashion.

No new engine for now, this one only has 14,000 and I need to get a little more use out of it. I have a local kid who I frequently use to do valve and carb adjustments and he is on his way over to help me remove the engine and the heads. It should be out in a few hours and then I'll know a lot more about what is going on and should even be able to post some pictures.

FYI We did the compression test and leak down test a week ago and ruled out the piston and rings. If you recall from my previous post, he banged on the valves and thopught he freed up some carbon, because the engine started running fine, but the problem has returned. Stay tuned.

Troy

when i was 16 my buddy and i could pull a vw motor in 15 minutes. we did dozens of them for a gas station the worked on VWs. I believe we got $20 each and that was good money then. We would put it up high on jackstands, he would lie on creeper and we would let the engine down, i would then grab his legs and pull him and the engine out.

LOL Bob. I refuse to grab this kids legs! Oh and the price has gone up a bit. I'll be giving him $75.

Troy, as I mentioned in my long post above, and then Roland followed up, do a leak down test, not a compression test. In a leak down test you inject air into the cylinder at TDC. If you hear air leaking through the carb's then it's an intake valve, if you hear air leaking through the exhaust then it's an exhaust valve and if you hear air leaking through the oil filler, it's rings. It's a lot easier than pulling the engine should it not be any of these items. If you don't have a leak down tester, they are relatively inexpensive at Harbor Freight. The only tools needed are an air compressor, the leak down tester and a spark plug wrench. Oh,, and your ear

Thanks Larry. We did do a leak down test and a compression test and the problem was with the exhaust valve. The engine is almost out and I'll know more in a little while.

Good, as I stated above about cylinder heads, ported and polished is great but, if you just want a good running engine, buy a new set of stock heads. Remember, the cc's in the head are very important and unless you have your cylinder head repaired, it's a "must do" so you don't alter your compression ratio.

Ok. So now I don't know what to think. The engine is out and the heads are off and there is no obvious problem. We even took the 3 and 4 exhaust valves out and they look fine and seemed tight in the guide. Roland suggested pouring some water into the intake and exhaust ports on the heads and looking for any leaks around the valves, but there was none.

At any rate, I'll take the heads in and have them rebuilt, including new seats and put it all back together.

Now I'll whine a little. It never seems like the problems I have a simple!
Pictures at the link below.
http://kvanasx.hopto.org/speedsterheads.htm

troy, could it be the carb to that cylinder is not giving it enough gas to ignite? you have covered all the other bases.

Troy... is that the same cylinder that had the valve carboned up ?
Might just be an isolated ignition problem to that hole or fuel delivery issue....it's always best to check and recheck prior to a tear down. It would be a bitch to put it back together and find it was something simple. ~Alan

I always checked my valves with solvent or gas, if its not mechanical( compression is good),then its fuel or electrical.Since each cylinder has its own fuel delivery that could be a problem , you can check the spark on a system scanner or strobe timing light (as mentioned above).I've seen some weird stuff using brand new parts in building hundred and hundreds of engines, Alan is right, its usually something simple, but you had to take it apart to rule out obvious stuff anyways, so don't feel its wasted time:)Pretty deep step cut in the heads,must not have much in the way of deck heights, or just to increase cc's in the combustion chamber to keep compression down, the heads don't look fly cut to much as the tabs are still there on top.Take heart the problem will surface.

One cylinder is nice and brown other has wet looking intake valve - is that cylinder 3?

In the photos with both cylinders showing, the left side is the #3 and the right is #4 (except the one where he is holding it). The one that looks wet is #4 and my problem is with #3. There is almost no ridge in the cylinders and you can still easily see the honing marks. There is very little carbon built up anywhere.

Based on the compression and leak down tests my mechanic did last week, the problem was with the #3 exhaust valve. This is what the invoice says:

"Found 30% leak coming from exhaust valve. Remove rocker arms and tap on valve stem with pressure in cylinder. Leak down dropped to 18% and compression up to 145lbs. Replaced wires and plugs, engine running properly at this time."

It is possible that it could be a carb. problem and that my mechanic was just full of it, but I have never had a reason to doubt him in the psat. However, Roland told me that there is a known problem with the manual choke on the Weber 40IDFs. They are not normally used and are not connected in my case. Apparently, a backfire can cause them to get stuck in the wrong position (not sure if it is open or closed), but the fix is to tap the holes at the bottom of the each carb and plug them so they are no longer a factor. I did that this afternoon. Roland can explain more about that. It seems like they are normally in the closed position and if one of them got stuck in the open position, it would allow more air in and make the car run lean. Since my car is backfiring out of the exhuast, I would think it was running to rich rather than lean and the unburned gas was igniting in the muffler. Anyway, I did what Roland suggested and maybe that will actually be the fix, but then I may never know if it really was the head and valves or the carb.

It's a good learning experience for me so I'm really not all that concerned about pulling the engine if it turns out to have not been necessary.

So I took the heads in this morning and the owner of the shop looked them over and said they looked fine to him, except that the #1 cylinder was clearly not seated properly. He showed me some carbon on the side of the head where it has been leaking and suggested that the head bolts may not have been torqued properly, or that the case may not have been properly machined. As for my #3 cylinder issue, he took out the valve and said it looked fine to him. He did say that it could be a bad ring that would cause an intermittent compression problem, but now I also have the #1 cylinder issue to sort out.
I've decided to go back almost to square one and start all over. We will reinstall the heads and do our own compression and leak down tests with the engine running outside of the car. Additionally, we will have a very close look at the Weber that is feeding cylinder #3. Arrrrrrrrrrrrhhhhhhhhhhh!!!!

Troy-just my observation and maybe I'm just not catching on, but let me raise a point (or just ask THE questions)...
You stated in 2nd-to-last post: "Found 30% leak coming from exhaust valve. Remove rocker arms and tap on valve stem with pressure in cylinder. Leak down dropped to 18% and compression up to 145lbs. Replaced wires and plugs, engine running properly at this time." I would think that diagnosing/correcting issues re: "leak down" would be done first; then proceed on to the ignition, if need be.
And secondly: "...the #1 cylinder was clearly not seated properly. He showed me some carbon on the side of the head where it has been leaking and suggested that the head bolts may not have been torqued properly, or that the case may not have been properly machined..." I would take your cylinders, head(s) and case and obtain dimensions (observing tolerances/wear limits) and see how things measure up. I would want to establish a baseline first then proceed forward to the "process of elimination". These things can be mystifying sometimes-on the other hand sometimes it just a bad gasket. Go figure.

Lot of good (and sometimes conflicting) info here, but I think that, right about now when you've had that engine apart,

what....twice?....

and since it's already apart, I might re-ring it (or at least pull the #3 cylinder and check the rings on that one only) and send BOTH heads to a good machine shop and have them do a valve job (new seats, new guides and new valves and lap them in). I get the feeling that either #3 valve stem is very slightly bent, or has a slight ridge on it, catching just as it starts to seat. Hence the 30% leak that went to 18% when tapped - if that ain't the valve, then I don't know what is. It would also become intermittant in time. These parts should all cost under $100 bucks and it's cheap compared to pulling it apart a couple of more times, isn't it? (triple that for installation)

Another thought on the rings - I haven't seen a lot of "intermittent" ring problems - usually, once they break, that's it. Maybe Larry's seen some ring symptoms come and go (he's seen more engines than I have), but I haven't.

One thing I thought about a while back and I don't know if you've checked, is a faulty plug wire or distributer cap, especially if you're running 40,000 volts ignition or higher from a "hot" coil. Stock (and some cheaper import) plug wires will break down over time and become intermittant, depending on a lot of factors, but especially heat and humid weather. For instance, I used to use Bosch wires on my "Magna Spark" system and would see them break down in about 18 months. Finally bought a set of Taylor 8mm HEI jobbies four years ago and they're still going strong. What a difference good quality makes! I also wouldn't rule out a bad, new sparkplug, if you've changed them - happened to me more than once in the last decade, and they're cheap so throw in a new set when you put R together!

Good luck

Gordon

Do you think it could be a "frozen" valve lifter on the cam? Maybe overheated or gunked up and stuck in its bore? If you rotated cam so its not applying pressure to lifter - you should be able to rotate the lifter and push it in some.

I believe it was stated that your mechanic tapped the valve with a hammer, and the valve started working (some what) again.....My first impression would have been tight valve stem to guide clearance, or a minor deflection in the valve stem's run out....With today's no lead gas, this is about all I could come up with......

I didn't realize the problem was intermittent if sticking valve (as mentioned) or rocker arm,I've seen both.

I'm taking the entire engine with all the bits and pieces in to a very well respected local VW mechanic, who should be able to sort out what is going on. It's probably going to cost me, but I'm tired of screwing around with it and just want to get it fixed.
I'll post about it when I find out more.
But I do want to thank all of you for all the suggestions. That's is what is so cool about this site. I belong to a local VW list and there is virtually no interaction among the members.
Thanks again.
Troy

Troy -- it's a little late to ask at this point, but just by chance when the engine was running did you shoot a few puffs of starter fluid down the throat of #3 carb barrel? Did it run on the starter fluid but not without it? If yes then you probably have a fuel delivery problem. Especially since you now know there's nothing wrong with the valves and by the looks of things nothing is going to be wrong with the rings. And the rings wouldn't completely kill a cylinder anyway.

I gotta tell you, I just finished solving a very similar problem myself as recently as Friday. I took my carbs apart over and over and over again and couldn't find out why it was that I would loose a cylinder. In my case it was #1. I could tune the engine and balance the carbs perfectly. But when I took it out and started sporty driving the engine started crapping out and I'd limp home and discover #1 dead. Worse, I could fool around with it and it would run nice again, until I'd start sporty driving. Worse yet sometimes it seemed to just take care of itself, until I started sporty driving again.I did notice that the dead cyclinder would immediately pick up with puffs of starter fluid which kept sending me back to ripping apart the carbs.

Friday, before putting the carbs back on again after the zillionth tear-down I decided to run my fuel pump (electric) and see how long it took to fill half a gallon jug. Shocker!! There was barely a trickle of delivery!!

I changed my pressure regulator from 2-1/2 to 3-1/2 for a huge difference in flow. Since Friday I've driven over 100 miles of serious romping trying to make it do "that thing" again. It doesn't!!

All along the problem was I was running out of gas. Maybe something clogged my regulator a little and changed what was probably marginal fuel delivery to insufficient. My #1 & #2 are end of the line for fuel delivery -- in other words #3 & #4 carbs are filled before #1 and #2, so that was the side that starved the most.

All of that work and it just needed a click on the fuel pressure regulator. Duh!!!

Now we're getting somewhere! My new mechanic took one look at the head and proved to me that it was leaking. He flipped it over, poured a little liquid over the #3 valves, blew some compressed air into the exhaust port and we watch bubbles flowing from around the valve. He also pointed out lots of other issues with the way my heads were cut and did some calculations that indicated my compression ratio was about 7:1. So it looks like we are going to be replacing the heads and putting in new rings and balancing the pistons and rods. Also, I'll be getting a new cam that is more suitable for a 1915cc engine. According to him, it will be a signifcantly stronger engine.

Troy, if your mechanic is going to install new rings then he has to hone the cylinders otherwise the rings won't seat. If he's going to that trouble, weigh his cost to hone the cylinders and buy new rings verses buying a new set of pistons/cylinders (typically $300.00 for Cima/Mahle ) .

In either of these scenario's, I'd opt for the new components.

Since you're getting a new cam that the mechanic "says" is better, how does he know that? Has he split the case and removed your existing cam for inspection?

I would wait until the case has been split before you commit to a new cam. Is he going to grind the lifters or is he going to install new lifters? If you install a new cam then install new lifters, they are ground from the manufacturer in a convex configuration then hardened. If he grinds the lifters then they need to be heat treated to sustain the pressure of the cam lobes rubbing on the face of the lifters.

OK, now that the case has been split to install the camshaft, I'd also opt for a balance job on the rods, crank and pistons (plus the wrist pin bushings in the rods should be checked and probably replaced. The crank needs to be micro polished and all new cam, rod and main bearings installed. (provided you're engine case is good) DON'T let him align bore your engine case. It will eventually cause low oil pressure.


Also, while the engine is out and split, now's the best time to have the case cut and tapped for a full flow oil system.

A little correctly done head porting (mathcing manifolds with ports)can yeild huge results with the correct cam,carb,compression ratio combination and balancing as Larry mentioned.I know this can be a touchy subject with builders but I think if you have the case align bored correctly by a qualified VW machinist using the correct tools and taking the centering of the tool seriously you can be ok. Its true if not done right it can cause low oil pressure,cam gear alignment problems,wrist pin wear ect.Its either cut right or not.Rimco has done a good job for alot of guys with "real race" motors,so has Jason at VW Paradise. Not everyone has $600-800 for an new case, if money's no prob then a new case is always best, just expensive. Troy, just have the case checked out well,thrust wear and warpage between halves depending on previous balance job,cleanup decks ect.

Thanks Larry.
The new cam is to replace the stock cam that came with my 1915 and the lifters will also be replaced. There is nothing wrong with the old cam except that it is stock.

The two lessons I have learned here are:

1. Don't ever take your engine out, because it's a can of worms. If you're going to do this, then you might as well do that and if you do that then you better do this too and on and on.

2. What ever you thought it was going to cost you to have your engine fixed is wrong, it's going to be waaayyyy more.
Troy

2. What ever you thought it was going to cost you to have your engine fixed is wrong, it's going to be waaayyyy more.
Troy

I'll second that!

Greg, when I had my VW engine rebuilding (side business) I consistently used Rimco. I've had some good work and some very poor work performed by them. I once had to eat an engine I rebuilt because I had the case aligned bored by Rimco. Oil pressure went to "0" and the engine fried. I had to buy a new case and totally rebuild the engine at my expense.

I know sometimes it works out OK but I'll probably never have another engine case aligned bored. I've had better luck Not alignboring and just replacing the bearings. But, that's just me based on my experiences.

Troy, I don't mean to harp on the subject but are you sure it's a stock cam??? Most engine builders will at the very least, install a 110 cam when they build a 1915cc engine

Yup I believe it, I always did my own machine work at the shop(everything except port and polish).I wont deny its the safest way to go , new everything from a quality supplier is great fun and less work, just clean, dry fit everything, and assemble with great love and care! A little off topic, I was noodling thru Samba and discovered a thread about the "million mile bug" and the owner Albert Klein from Pasadena, I forgot all about him, he came into the shop in the early eighties and I built his second or third to last motor. Years later he called and said he got a free Fox from VW for setting the record! Thanks VW :0 ! Anyways I remember his case had at least a .20 over line-bore and he got I don't remember exactly but it was close to 100k or more on that little motor. I think he went thru 7 or 8 motors. Nice guy, I wonder if he's still around? He was happy with the job tho. Kinda fun!

Larry.
He was willing to bet me that my cam was not stock, so he took it out while I was standing there and was surprised to see that it was stock. The only reason I told him that I thought it was stock was because Roland, who works on a lot of Kirk's engines, told me it was and I guess he would know.
Anyway, things are starting to come together now and I am confident that he is building me a 1915 that will be much better than what I had.
Troy

Do I hear "MEXICRATE"?????

OUCH!