By Zippy (Zippy) (205.188.196.31) on Monday, June 25, 2001 - 04:46 pm:

OK here's the story. Following "SOS Engine breaking up", I seem to have solved the problem thanks to your help (or mabye I misinterpreted it). So I was running down the deserted street at about 5000 rpm in second gear when there was a subtle pop and a moderate loss of power. I pulled over and noticed that the dip-stick was partially out of the hole and oil had sprayed everywhere. I reved the motor up again and it popped again, more oil. I was hoping for the easy solution so I unplugged the PCV hose and plugged it. The air flow from the hole in the rocker-arm-cover at idle was distinctive. As I reved it up the airflow became more of a wind as oily air rushed out. Pluging the hole, even at idle will result in the dip-stick popping if you wait a minute. At high revs the stick will pop very quickly. I interpret this as EXCESSIVE BLOWBY. At his point, my oil appears to be ok, meaning no water is in it. My coolant also appears to be ok, although I have an overheating problem that has not been conquered. Yes, the thermostat works. No, the water pump is not leaking and it did have good impellers when I mounted it. The cap is 14 pounds. The radiator is moderately clear. The fan is always on. The only thing I can think of is that the bypass around the leaking heater core is allowing water to skip the radiator, but I crimped the hose and it didn't seam to help much. Or mabye, it has somthing to do with the damn high crank-case pressure.

What is going on!!! Please, somebody give me some good news.

Roger

By Charles (137.219.16.107) on Monday, June 25, 2001 - 08:32 pm:

It is obviously blowby but caused by what?

Most likely;

Broken rings or Broken ring lands.

Do a compression test to see where it falls down.

By Farfignugen33 (12.110.136.92) on Tuesday, June 26, 2001 - 08:54 am:

well I don't know if I could shed any light on this, but, Charles is right, get a compression test done for sure. When I had an excessive loss of power and overheating, the compression test clearly told me I had to replace the head gasket. That solved my power loss and overheating. I've never heard of THIS kind of blow-by though...yikes, hope somebody can help you more.

By Zippy (Zippy) (152.163.213.63) on Tuesday, June 26, 2001 - 05:18 pm:

Dang it. I ran a compression test with one of those cheap push-in-the-hole type devices. All four cylinders came in at very near 110 psi (all equal within the precision of the tester) (I can't find my good tester). Just for grins, I'll tell you the procedure. Who knows, mabye there is some subtlty that I missed. Remove all four plugs, put the device in a cylinder, have wife pretend to start the motor for 4-5 seconds while I hold gage, read gage.

So here is the question: Am I just hallucinating this whole problem? How much blow-by is normal? If I had no compression in one cylinder I would know what to do, but now I'm stuck. I've rebuilt about half a dozen engines. I am not a dolt. What part of the puzzle am I missing? Does higher compression leads to more blow-by and I'm just freaked because I build motors with 7-to-1 and now I'm over 10-to-1. By the way, what compression ratio produces 110 psi in the cylinder of a cold motor with the butterfly closed?

Anybody need a Civic to take parachuting?

Roger

By Charles (137.219.16.107) on Tuesday, June 26, 2001 - 05:49 pm:

A 10:1 compression ratio should give more than 110psi even with the throttle closed. Should be nearly twice that much.

Even the worst sort of gauge shouldn't give a reading that low (unless you have a crazy big cam). How long since rebuild. Could the rings be shot, What were the ring grooves like when you rebuilt it. How much clearance did you have? Some crankcase pressure is normal, does the dipstick blow out all the time (ie with the rocker vented to atmosphere)? Take out the mesh filter in the rocker cover and give it a clean also.

Is there too much oil in the crankcase?

By Nikolaj (213.197.6.122) on Tuesday, June 26, 2001 - 11:46 pm:

Interesting story... I have a second gen, of which I had a power-loss-problem also (still have it, but I'm tearing the thing apart as we speak/write/read)... I did a compression test, pretty much the way described here... They all came in at about 14 (bar??)... I thought this was kind of very high, but the dealer told me it should be 13! Aren't these all very high values compared to the EB? And is the device not so specific, yet still usable to check if all cilinders are the same, or is it just a very untrustworthy piece of equipment??
Just wondering all this...thanks.

By Zippy (Zippy) (64.12.104.37) on Wednesday, June 27, 2001 - 05:01 am:

Thanks for your help so far. My engine specs are in the thread "SOS Engine breaks up at high rpms" The engine has about 1.5 hrs on it, all tuning and testing plus a fair amount of break in running at various rpm from 1000-3000. The rocker cover vent is clean. I question the pressure numbers you gave me Charles. My '73 Nova ran about 80 psi if I remember right. Do we have a unit issue. I'll run a compression test on my truck just for grins and see what comes up. I'll also get a good gage tonight. Oh yeah, I'm going to warm Zippy up and do a test on her at running temp.

What about a cracked head??

Gimme more, Thanks,

Roger

By Charles (137.219.16.107) on Wednesday, June 27, 2001 - 02:42 pm:

Most motors with an accurate comp tester will show at least 180 with 10:1 compression. A city turbo with 7.5:1 compression will show 125-140.

A cracked head should not give massive blowby (unless it is cracked from the combustion chamber right through to the rocker areas in every cylinder). It is correct to assume all compression testers are wonky and that as long as the cylinders are within 15% of each other there is no problem.

However with your blowby there is a problem. It will not be head related (unless you have heaps of clearance on your exhaust valves) as head problems will let the pressure out of the combustion chamber (not force it into the crankcase).

Do you have any piston slap? Are the pistons and rings both brand new and matched sets, what is your ring gap like? I still think your ring clearance is a likely supect. Rings work by gas getting in behind them and forcing the rings out against the cylinder walls, to much or too little clearance stops this from happening and you get compression leaks. 1.5 hours is not too much run in time. What sort of honing did you use what grade, what sort of rings did you use, did you use a non additive oil for quick ring bedding.

Whatever happens I would not be taking my fresh engine with only 1.5hrs use over 5000rpm for any length of time, it'll just help glaze the bores in this early stage, if you used chrome rings expect bed in time to be a bit longer than usual.

I would say keep running it, keep the revs low, make sure cam timing is good (out a bit can cause low compression readings).

Charles

By Zippy (Zippy) (64.12.106.34) on Thursday, June 28, 2001 - 06:21 am:

Charles,

Thank you very much. I should have known better than to question your info. I got a new compression tester and did it again. This time I propped the butterfly open with a piece of wire. I got 180, 140, 160, 175 psi. My plugs look ok, but the #3 is slightly darker. I put a bit of 90 weight oil in number 2 and it went up to right at 300 psi and blew my new gage. I also noticed that the RPM you test at is important. Readings were notably lower with a low battery.

I honed it with a regular hone that uses 3 stones. I don't know the grade. Scuff marks were very attractive. I used cast steel rings. OK, I didn't (dont know how exactly) worry about ring gap and the pistons have 120K mi on them. I don't hear any piston slap (yes, I know what it sounds like, my wife's Dodge had it at 37K mi). The engine sounds very smooth. My head timing is good.

You think it may straighten out after running it a bit??? I'll go ahead and do that. Next time I do this (assuming it dosent straighten out) I would like to get some more advice from you.

On a lighter note, Darrel is giving me his engine. I'm fetching it this weekend. It will be nice to meet another first genner. I'll also get enough pieces to replace/fix some of my ancillary components (distributor, radiator). If I put the engine in my car, I expect that I'll be running by July 8 and make the autocross the next weekend.

Charles, I think you are right on with the ring thing. Please let me know what I can do to help set them.

Thank you all so much,

Roger

By Zippy (Zippy) (205.188.200.37) on Monday, November 05, 2001 - 07:44 am:

Hey all,

Good news, Zippy is alive and well!! Darrell's lower end had been transplanted into my car and is performing wonderfully. Smooth and quiet until I give it gas. After everything was together I reached in the window pulled the choke and turned the key. I let the electric fuel pump run for a minute to fill the carb then turned her over and she fired right up. It is good when things are good. During shake down the alternator/water pump belt popped off twice at very high RPM. The alternator pully is set back about 1/2" so I figure thats the problem. I should be able to put a spacer behind the pully to take care of it. Anyone dealt with this before? By the way, the old block, it is definately the pistons. Cylinder bore is too big for the pistons. Need new pistons.

Very Happy

Roger

Now I remember why she is named Zippy.

By Todd (63.50.56.145) on Monday, November 05, 2001 - 12:00 pm:

Hey Rog, you have truly given us some good news! Are you using a stock alternator? While you're there fixing the pully, why not find a 4" diameter pully that fits? Then get a crank pulley from a CVCC (smaller diameter). It slows down your alternator a lot. Only side effect is it's so slow that it doesn't produce voltage at idle. So your lights go a little dim at idle. Whoop dee doo. This mod alone was worth about 800 rpm in third gear.

By Zippy (Zippy) (152.163.213.47) on Sunday, November 11, 2001 - 12:28 pm:

All right,

What is the name of what you are doing when you take a gear as fast a it will go and stay there, floored? For example my speedo will register 35 mph after being floored first gear and 55 flored in 2nd. This corresponds to about 7000 (?) rpm. I am quite a bit over redline when I do this.

Any how, when I did this today my dip stick popped out of the hole. Now this was happening before but with higher frequency. I have the rocker arm cover crank case vent hooked to the big hole in the bottom of my intake manifold and I have a 1-way check valve in the line to prevent back fires into the crank case. This pulls a great vac into the crank case, when I turn off the motor you can hear air slowly squeaking down the dip stick hole around the rubber seal. If you break the seal a lot of air rushes in.

Does the intake manifold ever have a positive pressure in it, even very briefly???

Looking for suggestions, even stupid ones.

Roger

By ddechon (12.91.124.161) on Sunday, November 11, 2001 - 02:03 pm:

Hey Roger,

My dip stick used to pop out a lot too...but then I got married! HA!

But seriously...
Why do you have your rocker vent tube hooked up to your manifold? Is that a performance secret, or were you doing that to keep your dipstick down? Do you ever loose oil pressure?

In some areas your crankcase is supposed to have a small amount of positive pressure from your oil pump.

Darrell

By Adrian (Civicguru) (203.42.97.227) on Sunday, November 11, 2001 - 02:19 pm:

ddechon: The vent is supposed to be hooked up to the inlet somewhere. It's called Positive Crankcase Ventilation (PCV). The oil pump pumps and pressurised oil, not air, so should have absolutely no bearing on crankcase pressure.

What Roger is describing is blowby. This is where combustion gasses escape past the rings and pressurise the crankcase. It's not unusual to have the dipstick pop out at high revs, especially if your rings are a bit worn. Obviously you're getting more blowby and thus pressure than the PCV system can handle and the easiest exit for that excess pressure is out the dipstick hole (it's going to take the path of least resistance.)

By Todd (63.50.56.222) on Sunday, November 11, 2001 - 03:00 pm:

The fix is to add another vent in your valve cover, or simply put a spring on your dipstick to hold it down.

By ddechon (12.91.127.65) on Sunday, November 11, 2001 - 06:06 pm:

Isn't the PCV normally connected to the air filter case housing? The reason it's connected there is to help provide clean air in and out of the engine case, not a vacuum. The old cars of the 60's used to have valve cover filters. So you don't need a vacuum there. Connecting it too the manifold would create a vacuum which isn't normally there. If a vacuum is supposed to be there it would be called NCV. Plus I'd be worried about sucking oil into the manifold.

The vent is there to give the positive pressure a way out and to let the flow of oil continue upward.

Adding another vent would be the fastest fix, but it might do more harm if your vent tube is still connected to your manifold. You might loose important manifold vacuum through your vent tube.

I think you should find a free flowing alternate location for the existing vent tube, then find a way to increase your venting like Todd suggested.

Adrian, I don't mean to pick sides. It's just my opinion and I think Roger deserves to know what we're thinking. I do think your right about the blowby. Sorry if I come across as a car geek with an attitude.

Darrell

By Zippy (Zippy) (205.188.201.198) on Sunday, November 11, 2001 - 07:50 pm:

Darrell, no, I've never seen another PCV system set up like this. You are right about the traditional location. But on my last block I was popping the dipstick all the time and thought it might be blowby so I set up like this, thinking it might help and it did, a bit, because it draws more air. In PCV the P means always having a vacuum in order to prevent gas vapor from escaping from the engine and polluting the atmosphere. Positive ventalation is opposite from positive pressure. Diesel engines don't have these systems and my friend's old flat head has an oil cap vented to the atmosphere instead.

Todd, does this mean that you have had this problem, or heard of someone else with this problem??

I have a hole cut in the side of Darrell's old oil pan where he had an oil cooler set up. This seems to me like it might be suitable for a second vent. I am fearful to lock the dipstick in place for fear that I may blow a gasket instead.

I might try being a bit nicer to the motor.

Does the intake manifold ever have a positive pressure?? Has anyone ever had this problem?? Does anybody else have their PCV system set up like this or are you all hooked up at a more traditional location???

Thanks, Darrell, Adrian, Todd

Roger

By errol (205.188.195.54) on Monday, November 12, 2001 - 05:43 am:

1,Why are you shifting at 7000rpm?
2,There was only two honda shortblocks that I've had that the pistons WEREN'T damaged in some way! What I've seen is probably due to little or no (clean) lubrication, fuel dilution or overheating. The pistons usually start deteriorating around the top ring land (they look like someone took a grinder to it) and that in itself sends tons of contaminates and metal shavings back into the equation.
I've even seen engines that 'sat' for a long time that the rings kind of glued themselves into the ring land and never were expanding outward to the wall of the cylinder (Bigtime blowby!)
you may want to take your valve cover apart. There are 4 screws that hold the little cover into the top (the later ones are spotwelded) try not to damage the gasket and scrape all the 'crap' out and see if it flows better (it could be severly clogged)
On some of these newer Honda engines that these kids are building up with turbos, they are porting a direct line with a pvc to a 02 bung in the exhaust which causes a great vent and burns off some of the emissions.
Another thing you can do is a leakdown test for each cylinder. (listen at carb for intake valves not seating and Exhaust for the exhaust not seating, or a burnt valve)
It sounds like a rebuild is awaiting...

By Todd (63.50.56.54) on Monday, November 12, 2001 - 08:49 am:

Yes Roger, I have seen this problem. At that rpm, you are simply creating more crankcase pressure than the stock PCV system can handle. Just wait til you start tossing the car around at an autocross and all the oil gets blown out the valve cover. I made an extra vent hole next to the stock one on the valve cover, then routed both hoses to a catch can. I think this is all normal with the level of performance you are getting out of your 1200, not excessive blow by.

By Zippy (Zippy) (152.163.213.177) on Monday, November 12, 2001 - 08:03 pm:

Todd, I an very glad to hear that this is not completely abnormal. What do you mean by catch can? Just an air tight can between the rocker arm vent and the intake manifold? Sounds easy.

Errol, I cleaned the cover about a year ago when I started playing with this car again. It was totally clogged and I believe it is the reason I parked the car five years ago. When it clogged all the gaskets popped, oil and water went everywhere and I put it away.

Re: the hot new turbos... The exhaust stream has positive pressure, so how do the gasses get out of the block. Do they still use a PVC system?? If they do it seems that at low rpm you would wind up channeling exhaust gas back into the manifold. Or do they put a check valve next to the exhaust pipe so that the system only passes gas out to the exhaust pipe when under a higher positive pressure in the crank case. Or am I thinking about this incorrectly because the turbo screws with the pressure in the exhaust stream.

Thanks, Roger

By Todd (63.50.56.45) on Tuesday, November 13, 2001 - 04:22 am:

They mount the PCV tube at a right angle to the exhaust stream and the flowing exhaust draws the vapors out. You know, the Bernouli effect.