a slightly different heater topic - slooooow warmup

[valvecovergasket]

ive searched all the threads i can find, and most deal a bit more specifically with the gassers.
i know the diesel stuff is a little less common, and ive had these NA early diesels in mk1s and know the heat takes some time to come on... but real quick here is my setup -

'83 westy 1.9l NA swapped diesel, originally the van was a 1.6l diesel.
cooling hose layout is the original 1.6l stuff, with the original 1.6l expansion tank, new pressure cap, overflow tank. system holds pressure (verified with one of those air-lift type coolant bleeders).
the engine failed an oil cooler according the PO and his stack of receipts, and the shiny new oil cooler on the engine.
there was still a little slime left in the coolant and as the van is new to us, i thought it worthwhile to drop the coolant and flush/clean. that was a success, and its all clean now!

it took some time to bleed but using the air-lift/vacuum/suction method worked great and i verified the system doesnt have any leaks. comes up to pressure, and sucks the coolant back out of the overflow on cool down.

the heater has always been really lazy, and the van very slow to warm up, even before my draining/filling. i originally thought what the heck ill throw a new tstat in while i had it drained, thinking maybe that was past its prime... no change.

the van also doesnt have a rear heater, just the front heater core in the dash. im thinking something related to this coolant flow may be the issue... ? missing a restriction somewhere?

with ambient temps during my commute getting into the low 40s i would like some heat, mostly for defrost

i have a vdo coolant temp gauge from the PO that ive been using to monitor the temps, a bit more accurately than the dash gauge.
if i leave the heater valve wide open/full heat request, its basically impossible to get the water temp up to 180 when going 50mph. itll warm up, albeit very slowly, moving in stop/go traffic.
if i leave the heater off, things warm up a bit quicker, though still not all that quickly comparing to my old diesel mk1s.

do i need to block the fresh air inlet to the heater box with these ambient temps?
did the diesel vans have worse heat?
did this thing come with a rear heater - that the PO maybe deleted incorrectly causing some funky radiator bypass condition?

thanks!

[DanHoug]

the small VW diesels suffer heat issues. there is so little waste heat that a heater core acting as a 'radiator' can cool the engine down so your temp gauge falls. some of the TDi models had an electric element inline with the heater core to add extra BTUs to the passenger compartment.

i ran a 1.6 diesel on veg oil all year round in essentially arctic temps. it'd take me a good 20 miles to get the cab warm of a tiny Jetta. a van? uff ta.
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[djkeev]

Wasn't the auxillary heater standard (or a very common option) with the diesels?

Dave
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https://www.thesamba.com/vw/forum/viewtopic.php?t=482968&highlight=74+super+vert

[crazyvwvanman]

I would get a new 87c thermostat and put it in.

The diesel fired aux heaters were only common in markets where they were needed. Northern states and Canada mostly.

The 82 and 83 diesels didn't get the rear underseat heaters. Instead they had a plastic center floor duct that fed from the dash heater to the rear compartment area.

Mark

[valvecovergasket]

thanks guys, sounds like im not totally offbase ..

for reference, it has a brand new tstat in it - i figured id replace that while i had it all apart anyway.

if i leave the heater valve closed/heater off the whole drive, warmup time is decent-ish in this weather, and once at temp it tends to do a fine job staying there.... unless the heater is turned on going down a hill then it over cools again haha

i guess the relatively large heater core on these, being fed ram air at the front of the van, is just too much cooling with these ambient temps. sort of makes sense.

i guess i need to put one of the vanistan fresh air blockoffs on my christmas list! haha


as for aux heaters, it has the DA6 diesel eberspacher that appears to be factory/dealer installed/original.
it has a lot of cut wires and capped off connections around it but the fan does work when i twist the aux heat knob at the dash hah
i think thatll all be for sale eventually for someone else to use as parts.

[crazyvwvanman]

My point was to make sure it is the correct 87c thermostat and not one of the lower ones, like 80 or 70. It needs to have no bleed hole as well.

Mark

[rmcd]

I have exactly the same problem with a few nuances. I have 87 with an ALH tdi motor swap. I have closed the front vent as part of my small car ac install. I also have the oem rear heater.

I’m buying a cheap Chinese diesel heater as discussed in the other heater thread.

Here is the thread.

[valvecovergasket]

[?Waldo?]

The ALH engine (TDI) dumps about half the waste heat into the coolant compared to your 1.9 IDI engine.

Preventing outside air from running through the heater core should help warmup times but it really isn't as simple as blocking the inlet. There is no recirculate feature to the stock vanagon heater system and the heater air has to come from somewhere.

If your thermostat is working properly then blocking the air to the radiator has absolutely zero effect on warmup times. It also has zero effect on engine temperature unless the thermostat gets to the fully open position (rarely happens in colder weather) in which case it can cause overheating.

It sounds like you have a non-functional or incorrect thermostat.

[Steve M.]

you might want to get the kit from Vanistan's IntrepidOverland.

https://intrepidoverland.com/shop/cabin-air-control/

Blocks off the cold air coming in the front.
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[Wildthings]

Assuming it was used on a Diesel then removing the baffle plate from the heater box should increase the air flow through the core and thus bring more heat into the cab. You could also add an pump to the heater circuit to increase the coolant flow through the heater. As mentioned get a higher temperature thermostat without a weep hole and check the temperature of your block during warm up with an IR gun.

Do check the temperature of the inlet hose to the radiator during warm up as well to verify it is remaining cold. If it warms as the engine warms your heat is being wasted. Do you have the pan under the engine compartment to keep cold air from blowing across the engine.

[valvecovergasket]

edit - i think my first post was maybe a bit less than clear on the behavior with the heater off. but im generally happy with the warmup times in that case.

[?Waldo?]

I've owned, operated, maintained many of the diesels in Vanagons the various varieties of Mk1-Mk4 IDI and TDI engines.

Your 1.9 non-turbo IDI engine should come up to normal operating temp very quickly unless it is down into the lower teens in °F and should blast burning hot heat from the heater. The IDI waste heat is significant and has no trouble keeping up with full-blast heat unless it is really cold out.

Blocking off the heater input will block the only inlet for air to the heater.

BTW, I find the lack of capitalization a bit irritating to read and inconsiderate so at this point I will opt out of reading your posts. Good luck with your issue.

[valvecovergasket]

[valvecovergasket]

having another look at the van, and the bentley hose layout for the diesel and i think ive spotted my issue.
a bit hard to describe in words but long story short i think theres a tstat bypass with the way the hoses are laid out around the oil cooler.

the 1.9l has the fwd style j hose (between the head outlet port and waterpump) with the t in the middle that normally goes to the oil cooler. PO has this hooked up.
the radiator to tstat hose is the van one, with the t that goes off to the oil cooler. the large head -> radiator hose has its second t blocked off.

anyway, this looks like a big tstat bypass to me as the water pump will suction through the oil cooler and bypass the tstat for however much flow can go through that thing.
im unsure of exactly how the heater core on/off plays into how this all flows but ill fix this bypass as a first step.

[Gnarlodious]

[valvecovergasket]

Gotcha - that makes sense
I'll have a look around for the reroute. Definitely wrapping the hoses will be on the to do list when we do the engine swap next year

I swapped the hoses around on the oil cooler last night so I'm not bypassing the tstat anymore and that made a big difference in the speed of the warmup while stationary.
Perhaps Ive stumbled on to the reroute, as my routing now matches the front wheel drive cars, just minus the metal distribution pipe.
I'll have a chance to take it for a spin tomorrow and see how it does with the heat on from a cold start while moving.