overheating and smoke out the tailpipe

[aksyta]

I'll start with describing the engine

1500 single port single relief case, rebuilt within about 40k miles
One heat riser disconnected on the 3&4 side from exhaust and plugged
Non-doghouse shroud
no thermostat , likely no flaps
Bigger oil pump, likely 30mm
Oil filter pump bracket (the heat riser tube on the exhaust is cut and closed off to clear it)
Deep sump for about 6.5 quarts of oil total
Manual transmission
Solex H30/31 carburetor
205P distributor, vacuum can is toast but mechanical still works
VDO oil pressure and temperature gauges

Usually the engine gets up to about 210 on the highway on a hot day (90+) and stays cooler driving on city streets, but it started to get up to 220+ and idle lower while driving around town a couple weeks ago on a hot day. I pulled off to let it cool down a bit and drove home, it started to idle lower again just before getting there. Oil pressure got a little lower than usual

So I did some things that might remedy overheating:
Checked and set valve clearances where needed to .006 (all were within about .001)
Set timing static to 0 degrees with a probe light
Checked that the relief piston is not jammed
Set the belt tension to 1/2" deflection (it was a little loose, 3/4" deflection)
Cleaned the carb
Covered some gaps in the tin with high temp metal tape
Used some glue to stick the seal around the bay to the tin (it had been coming off in spots)
Changed spark plugs and wires (I had new ones sitting around but hadn't changed them, and the old plugs looked pretty fouled)

I did a couple test drives during this, the oil still got hotter and the idle sometimes dropped just driving around town. On the final test drive after doing everything listed, the oil didn't get too hot, but the engine started to idle lower, and when I got home there was smoke coming from the tailpipes.

That was just yesterday, today I tried to start it up and go for a drive to warm it up for a compression test. The engine started fine but did not idle and would die without some throttle applied. I set it at the third step on the high idle cam for a while, got the oil up to about 150. I ran the compression test and got 150 psi on cylinders 1 and 2, 130 on cylinder 3, and 135 on cylinder 4. Each cylinder took a fair bit of cranking to reach the it's max, only rising about 5-10 psi per compression stroke. The new plugs were pretty blackened all around, but the tips of 3 and 4 were more oily than 1 and 2. The left tailpipe (on the 3 and 4 side of the engine) seemed to smoke more.

I'm thinking of getting new 1600 cylinders and pistons, since they're fairly cheap and should fit the engine. Also, getting the engine out, taking it apart a bit, and investigating might give some insights into why it started overheating now. It's been on long highway trips loaded with stuff or people on hot days without trouble before.

[vwoldbug]

Does it have real big deep sump. Is the choke working properly and make sure it's not flooding . Check and see if the oil is diluted and overfilled . Is the smoke blue or black from the tailpipes . Lastly check cylinder leakage if everything else is ok.

[aksyta]

The deep sump is pretty big, brings the total amount of oil needed to about 6.5 quarts. The choke seems to be working, it's automatic so when it's hot like today it opens fairly quickly. Oil is near the high mark on the stick, and it kinda has a burnt smell to it. The smoke looked blue yesterday and today, didn't smell too much like gas, it smelled nasty almost like burning plastic.


There is some blowing out of the oil breather and filler cap, but when I cover them it doesn't feel like there's pressure. Also there's a little smoke/steam that blows out of the cap.

[aksyta]

Put the plugs back in and ran it, now it's backfiring and idling at borderline stall. I'm going to get some new wires and maybe plugs too. Checked the timing and it was a little off, put it back to 0 and it's still really rough and makes some pops

[bobinphx]

Idle all over the place, backfire and overheating.
I would suspect a fuel issue.

might want to open the carb up and have a look.

[vwoldbug]

Can we see a picture and are plugwires in correct order

[aksyta]

Swapped out the new plugs and back to the old ones. It ran badly for a bit, I had to turn the mix screw all the way in, fiddle with the air screw, and advance the timing some, but after driving a mile I had to open the mix screw back up to about normal and pulled the timing back to 0 static. Now it runs fine again, but still maybe a little hot.

[cletus_zuber]

[aksyta]

Here's some pictures.

I use a probe light with the clip on the case and the probe on the coil terminal where the condenser connects to for checking timing.

[cletus_zuber]

I'd set that distributor to 7.5° advance on static and go from there, then set it with a timing light to 28-30 at full revs.
_________________
1972 1302
HPMX 40's & 019

[goober]

"Each cylinder took a fair bit of cranking to reach the it's max, only rising about 5-10 psi per compression stroke."

"Oil is near the high mark on the stick, and it kinda has a burnt smell to it."

Check to make sure if you have flaps and that they are in an open position.

Check the tightness of your cylinder studs.

[viiking]

Why run a car without the obvious vacuum can not working? Are you sure it has mechanical advance as well?
_________________
1968 1500 RHD Lotus White Beetle since birth. In the hospital for major surgery
1966 Lancia Flavia Pininfarina Coupe - in the waiting room
Discharged: 1983 Vanagon, 1974 1800 Microbus,1968 Low Light,1968 Type 3

[sb001]

[ashman40]

When was the fuel filter last replaced?
_________________
AshMan40
---------------------------
'67 Beetle #1 {project car that never made it to the road }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!}

[Volks Wagen]

[Eric&Barb]

What weight of oil are you running?

You need to get the rubber boots that go just below the fresh air tubes to seal off the hot air under the engine from getting back into the engine compartment.

The one on the right of image below:

Pull the pressure relief valve piston and see if it is stuck or shows signs of sticking. Double check the length of the spring for stock length and pressure.

What size width fan are you using? Should be at least 29mm measures inside the outer rim. Using an earlier narrower stock fan is not good for your size of engine.
_________________
In Stereo, Where Available!

[aksyta]

I've also noticed the fan shaft has wobble, I can reach back and jiggle the fan a little bit.

Eric&Barb:
10w30 Valvoline VR1 oil.

I think I might have a pair of the rubber boots sitting around, otherwise I'll pick some up.

The relief piston slid out a couple seconds after I took the plug out, it had some marks from sliding up and down, and didn't seem to be sticking. I don't know what the spring is meant to be, but it looked fine, probably stock. I do have the big oil pump, so the bypass probably doesn't work exactly right even if it's stock.

No idea what size fan to be honest.

Volks Wagen:
The case ventilation is working, and the oil filter only has about 1000 miles.

ashman40:
The current fuel filter is 6-7 years old, it could be due for changing.

goober:
I'm not certain, but I think this engine has no flaps. I also can't see a thermostat or even a bracket under cylinders 1&2.

I've never checked the cylinder studs before.

The plan from here:

-pull the engine out
-check for crap in the fan shroud, tin, and fins that's blocking air
-confirm whether or not there are flaps, and if they're there that they're working
-replace the generator bearings
-check that the studs are all tight
-change the fuel filter
-add the rubber around the fresh air tube holes
-try different new plugs

[Eric&Barb]

Next time you have the engine out, pull the shroud to measure the cooling fan and at least install the thermostat flaps.

Polish up the oil pressure relief valve with fine sandpaper.

From post-1967 bus Bentley printed Volkswagen Official Service Manual

Not impressed with the quality of oil filter pump (CB Maxi 2 or stock VW Mexico are much better), but it should be fine at least for now. Are you getting about 10 Lbs. increase per 1,000 RPM increase? Hopefully you are not getting anywhere near 80 PSI at start up with cold engine.

Hopefully your carb jetting is not out of whack.
_________________
In Stereo, Where Available!

[jinx758]

Redneck tip #_ _ _

Use very small (like 4mm) vacuum hose split lengthways as a gasket to go around the tin holes for aluminum hose to pass thru. Did mine over 2yrs ago ... still good. Cheap solution, make sure v-hose is tight where it meets itself.

Please post solution when it happens ... following this post

Best of luck ... jinx
_________________
" It's not valuable unless you learn something from an experience. " Henry Ford

It's not unlike the same difference

You can't push a rope


VALVES (cold)
POINTS
TIMING
CARB (fully warmed engine)

SCRAPE ALL GROUNDS

My Craigslist rescued 100 footer :
1971 Standard Bug
1776cc dual port
034 distributor
38mm EGAS Carburetor

[aksyta]

Nothing much in the engine except maybe a dozen little leaves in the head crevices and some oil gunk. There were no flaps, and there's a missing nut on the top of the case. I got a replacement nut and washer already. Tomorrow I'll try to replace the generator bearings and check the studs. The fan is 29 mm on the outside between the edges, I had to convert from inches on the ruler to metric.