Thermo For F.I. Question_Help Please!

Leave the original for the flaps as it does what it needs to for the heads. Personally, I would use a thermostat in the oil feed to prevent it from being over cooled.

But to do that, you'll need to change the oil pump to one that has send and return bungs, put a plate where the oil cooler currently resides, block off the opening air flow in the doghouse, use a bumper mounted oil filter... external mesa cooler, fan with thermo switch.. The list gets long.

When you say, 'doesn't warm up', is it CHT or oil/block temp?

Depending on the weather, I don't expect my stock '73 to get an oil temp of 180F for at least 2 miles of highway driving these days. Ambient is around 70F now. A few weeks back when it was over 100F, barely the first turn on the highway I was at 180F and would peak at 235F crossing the bridge in the middle of my 25 mile commute I do every weekday.

I'll be doing the above mods in a few weeks to give a little stability to the oil temp.

I meant the oil temp.

Th heater does not begin to work until after about 3 miles.

I think I will try this. I will wait another month or so when it is colder.

VW thermostats came in three 'flavors,' 'Arctic,' or 'high latitude,' or 'Temperate,' and 'Tropic." They were also marked according to the temperature at which they opened.

First off, you want to audit your entire cooling system. There are a pair of deflector plates on the underside of the HEADS (not the barrels) that must be in place. See the photos in my blog.

The oil is not diverted through the cooler until it's temperature is high enough to lower its viscosity.

For your application I recommend fabricating a shutter to fit over the cooling-air inlet to the blower. The factory offered a kit of three as part of its 'High Latitude' package, designed to allow the air cooled engine to operate normally in Arctic climates. The shutters were steel and had a central opening, the largest being 75mm. In your case I would fabricate the shutter from aluminum and start with a hole at least four inches in diameter. ALWAYS install a LARGE tag indicating a shutter is installed on the engine. Big surprise if you forget to remove it in the spring-time :-)

-Bob Hoover

It has ACC-C10-5444 - BLACK COOLING TIN PR - TYPE 3 STYLE - ALL 40HP

1200CC-1600CC BEETLE STYLE ENGINES

of the little tin between the barrels.

Since it has the BLACK COOLING TIN PR - TYPE 3 STYLE , the following will not fit: VWC-131-119-358 - SMALL AIR DEFLECTOR ENGINE TIN RIGHT - ALL

1300CC-1600CC BEETLE STYLE ENGINES 1966-1979

And VWC-131-119-357 - SMALL AIR DEFLECTOR ENGINE TIN LEFT - ALL

1300CC-1600CC BEETLE STYLE ENGINES 1966-1979

Bob, Could you explain that? Are you saying that even though the pressure is high when cold, the flow of the oil is low, thus not much volume of oil is passing through the cooler?

I had a different behavior with my 2270cc T4 engine converted to upright cooling and true full-flow oil system. It retained the T4 oil cooler, but was a secondary to the external 92 vane. When ambient was under 60F and highway driving, oil temp never rose above 160F. I had to put in one of those oil bypass thermostats which solve the warm-up issue. On that car it was easy to do as the plumbing to it was exposed.

When I get around to redoing that beetle (now on blocks), the secondary cooler gets removed as the external one has no trouble handling the dissipation.

------------------------------------------------------------------

Sure. The above describes the behavior of the STOCK engine.

I missed the fact that you had done the full-flow modification.

On a full-flow system you would need to add shutters to the oil cooler (as when installing the engine in an airplane) or the Porsche-type thermostat to prevent the cold oil from circulating through the oil cooler.

Sorry if my speedy reading caused confusion.

-Bob Hoover

I thought the cooler was in series between the bypass valve and galley in the stock config.

----------------------------------------------------------------------

That is correct. But the stock oil cooler presents a high impedance load to cold/cool oil whereas the by-pass to the sump does not. Bottom Line: Flow THOUGH the cooler is zip... until the oil absorbs enough heat to lower its viscosity. When that happens the apparent oil pressure is no longer high enough to overcome the by-pass control spring and the oil has NO OTHER OPTION than to flow through the cooler. (Actually, the flow appears as a rapid series of pulses reflecting the output of the oil pump. The pulses are what wears out the bore of piston-type control valves which is why all modern pumps have gone to ball-type control valves. [Although VW did offer the control-valve piston in two over-sizes.])

With 30W oil the transition begins at about 170 degrees F., measured at the input to the oil pump. At about 190 degrees the by-pass to the sump is fully closed and the pulsations at the inlet to the cooler have disappeared. Between 190 and 220 (approximate, in each case) the system is completely self-regulating and as such represents a rather remarkable feat of engineering, needing only a seasonal change to 20W or 40W to make the system fully 'automatic.' For a time it was thought that a multi-grade 20W-50 was the Ultimate Answer for the stock lubrication system but after about three years it became obvious that the drain-back characteristics of the base-weight oil (ie, the '20W' part of the package) was contributing to accelerated start-up wear, especially in the valve train, and while VW did not abandon the multi-grade stuff, they issued a Service Note 'suggesting' a return to the earlier straight-weight lubricants if there were any signs of 'accelerated' wear in the valve train components (typically, galling of the rockers and rocker shaft and breakage of the washers).

-Bob

Bob,

Thanks for that great explanation.

---------------------------------------------------------------

You're welcome. But someone took the trouble to point out that I was talking about an upright engine whereas the question(s) had to do with the T4 :-)

Next thing, someone's going to tell me it's Friday... what's that you say?

-Bob Hoover