Cyl Head Temps Way too hot - '78 EFI Automatic

[TurkisMafia]

Hi Guys,

The heads on my motor gave way recently, so we did a full top end rebuild. I did one 300 miles round trip after the fresh build, and it just felt to me like the motor was hot. It did not fail or show any symptoms, but it felt and smelled hot. I since parked the bus and got the parts together for a CHT gauge.

I installed a TSC (the sensor connection) 4 channel CHT and used the dakota digital 18' termocouples.

Barring a gauge issue, it would appear I was correct. Just sitting idling, the #3 got up to 400, and a quick gentle run around the block produced temps in excess of 450.

All new wiring harness, new injectors, and a full test on the AFM and computer... everything appears to be functioning normally.

What can I do about this? I already fear I could've done damage to the new heads and rings. We checked the timing and set it to factory specs... and then tried retarding the timing to cool it off. With the timing backed down, there was a noticeable loss of power but no help on temps. Has anyone had success cooling these fuel injected motors down?

Thanks!!

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1961 Turkis Sedan, 1641cc
1963 Turkis Ragtop, 1200cc
1963 Turkis Vert, 1200cc
1963 Turkis Single Cab, 1600cc
1964 Turkis Standard Walk-Thru, 1641cc
1978 Westfalia 2.0L EFI Automatic

Turkis Mafia
Turkis Mafia Facebook Group

Sunny Sarasota, Florida

[BUSBOSS]

All tin in place? Engine foam seal? Flaps and thermostat working correctly?
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All the redemption I can offer, girl, is beneath this dirty hood
1976 Westfalia
1970 Karmann Ghia Convertible (sold - but not forgotten)

[TurkisMafia]

[Abscate]

COnfirm with a non-contact IR measurement, then move to AFR measurements to find out why you are as lean as shinola
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.ssS!

[SGKent]

the cylinders the farthest from the fan are hottest. Make sure that the fan is clean and doing its job.
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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

[SGKent]

duplicate post
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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

[my59]

Heads gave way, what was wrong with them might be a lead in here.
Air fuel mix if retarding the timing to say 28 doesn't drop theTemps
What's ambient? I can run 400 at 65mph when it's 95 out, or run 400 at 80 plus when it's 40.
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my59: Well son, my grandfather died before I got to drive it, so does that answer your question?
our79: sunroof bus w/camper interior and 2.0 FI
Other:'12 Jetta, '77 Benz 300D, and a 74 MG Midget.

[vacca_rabite]

[TurkisMafia]

Update to all: apparently I damaged all 4 probes going into the head. I knew they were fragile and attempted to be careful but…. Guess I need to replace and figure out a more careful way to install. The oval shape was allowing exhaust gas to overheat the probes. That being said, in inspecting the bellows on the thermostat, it would only expand from 33mm cold to 39mm when heated with a torch. Rat well says it should expand to 55mm when full hot. Flaps may not have been opening all the way on top of all this.
_________________
1961 Turkis Sedan, 1641cc
1963 Turkis Ragtop, 1200cc
1963 Turkis Vert, 1200cc
1963 Turkis Single Cab, 1600cc
1964 Turkis Standard Walk-Thru, 1641cc
1978 Westfalia 2.0L EFI Automatic

Turkis Mafia
Turkis Mafia Facebook Group

Sunny Sarasota, Florida

[borninabus]

you can't really install thermal couplers (ring terminal style) under the spark plugs without machining the boss in the head a bit bigger to accommodate them. it's only a matter of time until they distort and no longer seal when changing plugs.

take a look at where VW thought was a good place to measure head temp. there's a spot for TS2 on both heads, BTW. it may "not be as accurate" as under the plugs...but the temps you will see are much less stressful, will change almost instantly with the throttle and as with any other gauge, can still be used for trending.

sounds like you have some cooling issues to get a handle on first though.
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88 Van WBX, A/T - 13 JSW TDI 6M/T - 2012 Touareg TDI Sport

[SGKent]

Let the sender act as a sealing washer. The standard spark plug washer is beveled, and it will expand the ring.
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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

[LouFilia]

[airkooledchris]

to the OP and others, id always suggest just using the Dakota Digital setup under the #3 plug. It's what most others have and then you can at least do a better Apples to Apples comparison on numbers. Otherwise what you have is really only good for trending.

[raygreenwood]

[vacca_rabite]

The last few posts are on fire.

To use the ring terminals you need to cut a groove in the boss of the heads so that the terminal and the wire don't get pinched. You can use a dremel for this, or even just a round file.

You need to take the washer off the spark plug and use the ring terminal as the washer.

As to the head temp boss, yes that can work. Yes the temps will be lower. But its not the location I would use on my engine. I actually monitor both under the spark plug and at the head temp boss. On my engine (Microsquirt EFI) I monitor "coolant" at the head temp boss. Its used for warmup enrichment. I run a Dakota digital on Cyl3, a mere couple centimeters from the head temp boss.

There is ~ 50 degrees difference between the two until the engine is COMPLETLY heat soaked. By the time the boss is showing 400 you engine has really been cooking for a good long time.

Zach
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1972 T2 Bay Westy in restoration
1976 Porsche 914
196? Empi Sportster Dune Buggy