Stock 1600 DP rebuild, step by step

[Ducklips]

I noticed you placed the altenator pedestal louvered gasket toward the cylinders as per the Wilson book. Everywhere else I've seen says place it with the louvers down with openings toward flywheel. The book shows it this way, but says turn it 90 degrees toward cyl. What is correct???
_________________
Early 1973 Super sedan. 1641 cc (o\_!_/o)

I once won an argument with a women......in this dream I had.
The older I get, the better I used to be.

[maboyce]

In the Wilson book the text is wrong, but the picture and its caption are correct, and agree with the Bentley manual. The louvres open down and toward the right side of the engine.

[maboyce]

As of today, the oil pump cover or somewhere near it is leaking again, and the engine dies when coming back to idle from open throttle. I'm not really sure what else to do about that oil pump. I want to JB weld it and its cover to the case...

There is a small possibility that the leak is actually coming from one of the oil gallery plugs - I saw dampness there, though maybe not as much as I might expect if it were the sole source. I'll have to take the rear tin and the pulley off, yet again, to be sure.

[Ducklips]

[Ducklips]

[Glenn]

_________________
Glenn
74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
"You may not get what you pay for, but you always pay for what you get"

Member #1009

#BlueSquare

[Ducklips]

Thanks Glen!
_________________
Early 1973 Super sedan. 1641 cc (o\_!_/o)

I once won an argument with a women......in this dream I had.
The older I get, the better I used to be.

[maboyce]

I did some more test running this afternoon, having decided to get a handle on the running issues before going after the oil leaks. I'm glad I did, because others appeared or were identified - suspicious darkness that slowly developed under the fuel pump pedestal was indeed a very slow oil leak. There's a nice one around the oil pressure sender as well.

Today I couldn't get it to die coming off throttle as it had been doing before. The idle dipped as low as 750 RPM when coming down from 4000 RPM, but it didn't quite die. Because of the temperature outside (7 C / 44 F) I ran it with the preheat tube flap held open, and I think that made the difference. The last time I had frost on the intake manifold, and this time it started to form but then disappeared.

I did another leak check with propane, this time blowing it at the bases of the intake end castings. I also tried everywhere around the carburettor. I could hear no effect on the speed of the engine. That means no leaks, hopefully.

Once the engine was warm, I loosened the distributor clamp and moved the distributor back and forth to see what effect that had. I couldn't retard the timing much more than 5 degrees ATDC, the spec. for this distributor, without causing the engine to labour and threaten to die. Advancing the timing increased the speed of the engine, and from about 2.5 degrees ATDC on caused it to run more smoothly. I tested about as far as 10 degrees BTDC.

To test how much advance occurred under open throttle, I printed out a degree wheel and taped it to the pulley so that zero degrees lined up with the TDC mark on the rear flange of the pulley. I aimed the timing light, in tachometer mode, at the pulley and opened the throttle enough to bring the engine up to around 2000 rpm. The reading on the degree wheel (at the position aligned with the case seam) was 20 degrees. Because advance starts from 5 degrees ATDC, I gather that means there was 25 degrees of total advance at that speed.

I then let the throttle snap shut to see if the engine would die - it didn't.

I did the same thing again at 3000 RPM and 4000 RPM, and got 40 and 45 degrees of advance. This may be too much advance, but I don't know for sure.

While doing all of this, I noticed a sort of chirping noise coming from somewhere on the engine. My first thought was detonation, and my second thought was something rubbing that shouldn't be. It seemed to be coming from the rear of the engine rather than the sides or the front. I poked around with a mechanic's stethoscope, but couldn't hear the noise coming strongly from any particular part of the engine. I touched the valve covers, the alternator, the case right behind the pulley, and the fuel pump. There was a tapping from the fuel pump base, but it wasn't quite the same.

If it were detonation, wouldn't it be loudest at the cylinders?

I then tried to muffle various parts of the exhaust system with a towel to see if it was a whistling exhaust leak. The only change I could produce was when I actually covered the end of one of the tail pipes with the towel. It made the noise louder and more frequent. Covering either one had the same effect, but it was more pronounced at the left one.

My conclusion is that the noise is coming from the tail pipes themselves, or their connexion with the engine. I may take them off and put some muffler cement on their sealing rings and see if that changes the noise.

I did find a small exhaust leak at the front of the muffler on the left, as shown by the streaks of carbon coming out of it, but muffling it didn't change the noise.

Here's another video of the running engine, with better (but still not great) sound. I bring the engine up to 2000, 3000, and 4000 RPM as described in the text. The thing that falls off at 4000 RPM is the small spring clamp I had holding the preheat tube flap open.

http://vimeo.com/55488188

[75smith]

I would agree with exhaust leak-most likely at one of the heads, the mating surface is not flat and the gasket can't fill the void, so it chirps/whistles

covering the exhaust ends confirms this actually, because now your forcing the out of the leak-should help you locate it it actually
_________________
My 1975 Beetle Build Updated 8-21-12

My engine build

[maboyce]

A few more checks this morning:

I removed the tailpipes and ran the engine again. The noise was a little different, less whistly, and I couldn't affect it by covering the tailpipe holes in the muffler.

I did more hunting with the stethoscope, and was able to find that the noise was loudest at the flanges of the muffler where it joins the heads. The engine case was quiet. I tested several more points around the cylinder heads, and the loudness of the noise was definitely proportional to the distance from the muffler flange.

Just to make sure, I played with the timing again to see what the effect was on the noise. There didn't seem to be any, other than frequency as the RPMs went up. I'm pretty satisfied now that the noise isn't detonation, and that it is an exhaust leak. Valve train is another possibility, but that's all been apart and reassembled once with no change to the noise. It can be heard in the first start video on page five.

During teardown I do want to turn the engine over and make sure there aren't any pushrods rubbing on the flared metal at the ends of the pushrod tubes - I had to do some fettling during assembly to prevent that in several places, and I might have missed one.

Before I tear the engine down again, I really do want to use a gas analyser to make sure the mixture is adjusted properly. I read incidentally that a lean mixture will run better with more advanced timing, which I reported earlier.

[maboyce]

The other possibility here is that VW engines are just noisy, and I don't know any better. The ones I listen to on YouTube sound pretty similar, including various ticks and chirps. This guy doesn't seem alarmed at a noise that sounds very similar to mine, at around 2:00 when he walks around the side of the engine. Of course, he isn't alarmed that he's waving a lighted cigarette around his fuel tank, either.

[D/A/N]

[Boble]

Maboyce, you thank you very much for being so kind to take all the efforts of sharing this with us!!! I'm about to rebuild my engine now, and your photo documentation is priceless.


"Thread-of-the-year-2012"!!!

[ashman40]

[maboyce]

I tore the engine down again as far as removal of the heads, in order to deal with the oil leaks.

I drained the oil and replaced the plug, tightening it to 45 Nm.

I discovered that there was a lot of water condensing in the manifold heat riser tube, and that the left flange was leaking rusty water. Unless there's a good way to keep moisture out of it, I'm probably just going to use one of my non-hardening sealants on the flange and be done with it.

With the exhaust system off, I found that three of the four exhaust ports were quite sooty, but the #2 exhaust port was clean. There was a small amount of white residue, only.

Here are the two ports on the right cylinder head:

The plugs told the same story, #1 was sooty and #2 was clean and slightly brown.

I checked all the plug gaps, which were within tolerances, and brought them right to 0.6 mm as indicated on the spark plug package. (The Bentley gives 0.6 - 0.7 mm.)

I also turned the engine over by hand with the distributor cap off to verify that #1 TDC was where it was supposed to be, and it was.

The valve clearances on #2 were acceptable, with the intake valve right on 0.15 mm and the exhaust valve slightly tight.

With the heads off, the difference between the cylinders is striking:

3 & 4

1 & 2

At this point, I examined the #2 intake valve to make sure it was closing properly - it seemed to be. I didn't notice anything wrong with the seat or sealing surface.

I decided that the cylinder probably was firing, but was running very lean, indicating an air leak. This thread reports the same symptom, and suggests that an exhaust leak near the port can cause it even if the intake system is airtight. As of this writing, I've found at least one small hole in my welding where the heat riser tube meets the exhaust tube. Hard to see, and even harder to weld, but the carbon streaks are there.

As for the oil leaks, the big one from the oil pump happened because it blew the small bead of RTV right out of the crack. When I took the pump out I found it sitting on top with some Curil squeeze-out.

I replaced the stud that came out and held it in place with red Loctite.

I cleaned the surface and placed another bead of Dirko, this time leaving it slightly proud of the surface. The last time it was flat or even slightly undercut. I expect that without pressure from the cover holding it in place, its own adhesive ability isn't up to the job.

Leaving that to cure, I reinstalled the oil pressure sender with a generous helping of Curil T.

I removed the fuel pump, cleaned the surfaces, and tried Hylomar on it. (As suggested by Ducklips.) After application Hylomar has to sit until the acetone evaporates - then it's quite sticky. The viscosity seems similar to Curil T.

Because the pushrod tube seals had been weeping, I chose to risk using Hylomar on them. It seemed to be sticky enough to keep them from squeezing out of their seats under pressure, as they did when I used silicone long ago.

First they had to be stretched back out yet again...

I put Hylomar between the seals and tubes, as well as between the seals and the case.

Because there was a little bit of weeping from the inside of the heads, I also used Hylomar under the head nuts and washers inside the valve covers. These photos also verify pushrod tube seam orientation.

As usual the head nuts were snugged to about 7 Nm according to Wilson's pattern A, then tightened to 10 Nm and 24.5 Nm according to pattern B.

When the RTV on the oil pump was cured, I reinstalled the oil pump with a generous helping of Hylomar, and with new sealing nuts. Torque was 20 Nm.

It was followed by the pulley tin and the pulley itself. Its bolt again got red Loctite and was tightened to 45 Nm.

I put the rocker assemblies back on (25 Nm) and readjusted the valves to 0.15 mm.

When I put the exhaust system together, I used the red high-temperature RTV suggested by 'D/A/N' on the exhaust tips and also on the muffler to heater box connexions.

I also used it on the leaking flange.

I was going to try some different exhaust gaskets, Bugpack steel-bestos, but their outside dimensions were too large to clear the tinware. I should have known better than to expect something aftermarket to fit...

I re-used the same intake and exhaust gaskets. I have some new Meistersatz ones, but they are very rough.

The rest of the ancillaries went back on as previously described.

I took the liberty of installing a new belt, instead of the inherited one I had been using. I had to add six more shims to achieve the specified 15 mm of deflection.

I filled the engine with more Chevron Supreme 10W-30, with half a bottle of (very expensive) Lucas Break-in Zinc Additive.

[maboyce]

For the test run, I let the engine warm up until the condensation had evaporated from the outside of the intake manifold and the choke was completely open.

While the engine was still cold, I took the opportunity to check spark on #2 - it was nice and white.

With the engine warm, I first used an IR thermometer to see how hot the heads were running. I shot the exposed area indicated by the laser dot in the picture. I held the gun close and tried to get the dot right on the crack.

(Temperatures and pressures are given in the cylinder pattern
#3 #1
#4 #2)

For temperatures I got

93 C 97 C
97 C 100 C

Cylinder #2 is the hottest, more evidence of a lean condition. None of the temperatures seem to be dangerously high.

I shut the engine off and did a compression test. It took a few tries - I was timid about how far I screwed in the spark plug adapter, and that distance changed the readings significantly. I turned the engine over with the throttle and choke open, and kept turning it until the readings stabilised.

975 kPa 950 kPa
900 kPa 950 kPa

The Bentley says that all cylinders should be within 1.5 kg/cm2, or about 150 kPa, of each other, so these numbers are very good. Good compression should be 800-1000 kPa.

From this information I concluded that the short block is OK, and that the leanness had something to do with the ancillaries. It was at this point that I found the thread that I referred to in the previous post, and went looking for exhaust leaks again. I found the one on the heat riser tube, and believe it to be the source of the air leak - its location so close to the exhaust port makes it very suspicious. I removed the muffler and added more weld, lamely. It's very close quarters - I had to have 10-12 mm of MIG wire sticking out to reach the spot because the flanges fouled the MIG nozzle.

Now I have to wait for paint and RTV to cure. I may also check the exhaust flange for straightness.

[maboyce]

To fix the water drip from the heat riser flange, I put some Curil T on both sides of the gasket.

Another test run showed improved exhaust noise, but still not quite proper running. I also got a leak from the oil sump plate. At this point I decided it was worth my time to shell out to have the carburettor looked at, in order to eliminate a variable. I took it to Tim (advertises here as Volkzbitz), who lives about thirty minutes from me.

His report:

[Eric&Barb]

Put all bolts in that lower rear sled tin. Screws always loosen up and fall out of there.

The DH exhaust shell needs to be sealed up better. You can use hardware store foam rubber strip tape (like what is on the cooler) that is usually used for household door sealing.

The DH exhaust tube should have three rubber seals on it. Two of those seal and one keeps the lower end of the tube from getting cut by the edge of the front tin.
_________________
In Stereo, Where Available!

[maboyce]

I've sealed the oil cooler exhaust seams with 6 mm (1/4") adhesive foam strip, as per Eric's suggestion.

When working on another engine, I found that I had two different kinds of valve covers, one with a tab on the edge with a hole in it, and one without. I wanted two without for that engine, so one of the ones on this engine had to come off and be replaced with another one. Now both engines will match.

I ran it some more today, to make the cold start video, and it still hasn't leaked. When warm, I used the IR thermometer on the heads again, and got similar temperatures on 1 & 4 and 2 & 3. Since no one cylinder is distinguishing itself any more, I think I'm going to leave well enough alone.

As before,
3 1
4 2 order.

98 C 92 C
90 C 98 C

Cold start video

I apologise in advance for the annoying chirping noise. It's still there in person, but much quieter than it seems on the video.

I think that unless it starts leaking again or someone here points out some horrible flaw, it's done. Quite a learning experience - thanks to everyone who gave advice and encouragement!

[Eric&Barb]

Looks great! The chirping is a sign of one or more valves are too tight. Adjust them or risk burning up a valve.....
_________________
In Stereo, Where Available!