Heat/Defrost air flow

[creative native]

[Whaanga]

Ok - it’s been a couple of years since my original post - thanks for all the informative replies.

Even though it’s December (and as of yet we have no snow in Rochester), I’m still driving my bus- and the heat system is still doing ‘ok.’ I did source a heater booster fan, but I’ve yet to install it. Will I need the small flaps situated in the fan shroud or can I run the fan without them? (Mine are missing).

Thanks,

Jeff
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Late 1973 Bay w/a transplanted 914 Engine

[SGKent]

if the booster fan injects air like the factory one that is over the engine, then there is the potential at low engine RPM for that fan to reverse the flow of air thru the heater boxes from the point it it injected back into the shroud, but if it is an inline fan then it is only helping move the air. There are many people who lack the flaps in the heater boxes. If you eventually get some, you will want to use a small camera like the link below so you can verify that they open. I use a hair dryer on them to see if they will open. They can hang up otherwise because the install is not the cleanest and the parts are worn. That would be worse.

https://www.amazon.com/gp/product/B07PBF6DX5/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[Wildthings]

[RWK]

This is what I found while working on a 71 bus, see my response, found lots of heater tube insulation from the heater tubes in the narrow section of heat conduit above the beam, along with other FOs! after 50 years stuff starts comin apart!
https://www.thesamba.com/vw/forum/viewtopic.php?t=645004
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73 Type 181
63 Type 113
63 Type 261- 428 071
62 Type 241-378 025 178 530

[SGKent]

[Whaanga]

Hello,

I'm helping a friend work through some issues on his 1973 bus (with auto transmission). While his story is fraught with scary tales of purchasing a rebuilt type 4 engine from a shop in the midwest, the big issue he's dealing with is excessive heat. (This is a discussion for another post).

While he does have the heat exchangers installed, he is missing the heater boxes, accordion tubes, heat risers, etc. Would these missing components have any effect on the high temps he's seeing (via a Dakota Digital gauge)?

(I doubt it, but wanted to tap into the collected wisdom found here.)

Thanks,

Jeff
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Late 1973 Bay w/a transplanted 914 Engine

[SGKent]

probably not
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[Wildthings]

Have him set the timing at 28° BTDC @3800+ rpms, hoses off and plugged. If he is setting the timing by the book and parts are old, worn, missing, incorrect, etc the book timing will not work.

[SGKent]

the heater boxes pull some heat from the heads at the exhaust ports, especially on the 72-74 models. That heat is vented either under the bus or into the cabin when the heat is on. If he has heater boxes on but the tin is rotted away, then they are venting that heat under the heads. At idle it might cause the metal around them to get really hot but driving it is not going to cause high head and oil temps. set the timing like Mike suggested and see if that helps. Also - what is "high temps?" Too hot to hold the dipstick after a long run? Things glowing orange?
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[Whaanga]

Thanks Steve. The tins are good but all of the ductwork on the heat system is missing. After a 20 minute highway drive, the dipstick was warm to the touch, but not burning hot - you can hold it without discomfort. In terms of head temps, he's seeing 430-440* on his Dakota Digital gauge.
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Late 1973 Bay w/a transplanted 914 Engine

[Wildthings]

[SGKent]

430 to 440 is a tad hotter than many especially for this time of the year. Check the timing, make sure all the seals are there as Mike suggested. It also depends on speed. My engine runs 350F - 360F around town. But on the highway at 60 - 65 it comes up to 400F - 410F. If I push it to 70 - 80 mph it will come up to almost the temps he is seeing. It takes a lot of energy to push a sheet of plywood down the road at that speed.
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[Wildthings]

The thermocouple needs to match the gauge as well. The wrong thermocouple can give a reading that is either too high or too low.

[Whaanga]

We'll check the timing and make sure the thermocouple is correct.

AND - I did some more looking a see that the tin that surrounds the head around #3 cylinder is the wrong one and there is an opening built in that allows air to escape - and the sled tin does not connect correctly. I don't know if this will have a major impact, but it seems that every little bit helps.
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Late 1973 Bay w/a transplanted 914 Engine

[Wildthings]

Carbureted engines came with the extra hole in the tin, it was used to feed hot air to the carbs to help the engine warm up faster. It's pretty easy to make a cover for it using a lid from a large tin can and some tin snips.

[airschooled]

Surrounding #3 seems more like the earlier TS2 hole for the FI engines before VW moved it to the outer head area. Any plug works, I think I've used rubber blanking plugs before with good results.

Robbie
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