Bostig Temperature Help

[dogmandlux]

Hey everyone out there, first post after lurking in the shadows for years. Ive used the search and read all the post regarding operating temperatures, thermoswitches, and radiator fans with bostigs and have a dilemma I am trying to sort out.

I'm currently on a trip from Bellingham, Wa to Baja to do some surfing. Writing this from a friends house in LA. Swapped bostig into my 83.5 Vanagon L (now with camper interior) in April about. Been running really well with almost zero issues thus far, made it 800 miles before my serpentine belt parted, broke the nipple off the bottom of the overflow bottle. Drove into a town who luckily had the overflow bottle in stock and a new belt. Filled the bottle with coolant and drove on. It escaped me at the moment that when i was driving back and fourth to town, my engine cooled off and sucked air into the system from the overflow hose that was attached to nothing.

A few days later, I notice in San Francisco my temps a little higher than normal, though I was in Stop and go at the moment. Fast forward to LA, and my head temps are now running 220-240 in stop and go traffic, and now do the same just around town with mild traffic and stop lights. Coolant gauge up to about 3/4 and the fan kicks on (First time I've ever heard this thing kick on in the 4 years I've owned it. I've been burping Air from the system, and even paid a shop to flush the system, although they didn't get all the air out of the system which i had to do myself later. No air from the bleed screw up front right now.

Before this trip, Temps would be 185-200 driving around town, 200 on the freeway and max 215-220 when pulling up a hill at 65 and I dont recall the stock coolant gauge ever moving from right under the LED. I thought it was the terrible LA traffic jams at first but I've sat in traffic in Seattle for plenty long before without noticing the temperature really rise.

Ive talked to Jim and my logs looks good, but Ive seen on this forum either guys saying that their temps run 190-210 or other guys saying they run 220-240. At first i was sure it was just air in the system, but after the constant bleeding, only slight change in operating temps.

Im going to try the lower temp radiator switch, to kick the fan on earlier for now so i can continue on my trip, but has anyone figured out why there is a camp of people running slightly hotter? Im not overly concerned about running slightly hotter, I just wonder why the change occurred from running around 195 to running hotter than that. Its the sudden change that bothers me the most.

I've jumpered the fan and both speeds work.

Sorry for the long winded post, I hope a few of you bostig (or WBX) guys have the patience to read it as I felt the history part was important.

I'll try to respond as soon as i can to any posts, but I'm crossing the bored tomorrow into MX and hopefully will be a little busy surfing to get right back to the internet.

Thanks you!

[MarkWard]

The radiator fan is to make up for lack of airflow across the radiator. Highway speeds it should not need the radiator fan. Turning the fan on sooner, it may not shut off all other things equal. My fan cycle is about 10 to 12 F. degrees.

I don't have any Bostig experience. I recall a thread where the Bostig does not actually measure engine coolant temp. Anyhow, I'd want to check the actual engine coolant temp with a standalone gauge not dependent of the vanagon gauge or the Bostig ECU and sensor.

A good pilot trusts his instruments. 220 to 240F for coolant temp seems high to me for normal stop and go driving. Head temp, who knows?
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[kourt]

Howdy,

I assume you are getting cylinder head temps (CHT) from an extra gauge like an Ultragauge, or another OBDII data source. It would be helpful if you had a laser thermometer to measure your coolant temps at the radiator or a real coolant gauge with absolute numerical readings.

CHTs in the 220 to 240 range in warmer, more humid climates are pretty normal. My Bostig runs CHTs around 235 to 240 in the summer in Austin, TX, with coolant temps hovering at 180, up to 200 in stop/go traffic. When my coolant gauge gets to 200, the radiator fan starts cycling. This is normal.

You said you were from Bellingham, WA, where the temps are usually cooler (high of 55 today). Meanwhile in Los Angeles, CA, the high is 75 today. Have you factored this change? Because it's going to affect temperature readings, and will skew what you have come to see as normal.

Just a thought.

kourt

[dogmandlux]

Thanks for the ideas,

Yeah, I have read/thought that a reading with an IR thermometer would be a good idea. I've realized that I'm in warmer temps, but I guess for some completely unknown reason I didn't think that engine operating temps would go up hand in hand with ambient temps.

I read in an old post about a guy driving in florida in the heat with 200 degree CHT on average so I thought maybe the ambient wouldnt effect the engine too much unless you were in 110 degree desert or something.

Does anyone run/think that a lower temp threshold radiator fan switch would be a bad idea? I guess keeping the coolant temp more steady would 'feel' better for some reason. It seems like my idle CHT temp has to be around 220 before i ever hear the fan, and it doesnt seem like it would be bad to hold it a little lower than that. Jim thought i should go the switch route and put the toggle in.

edit:
And thanks for the detailed response kourt, The samba has always been helpful and its nice to feel it firsthand.

[SyncroButter]

How are you getting CHT temps... ultragauge? Are there other temps you can share?

Broadly speaking, I would not put in the lower temp switch. As others have said that switch is about cooling off when you are stopped or in stop/go, won't do anything for you at highway speeds etc.

When you lost coolant, what did you replace it with... distilled? Coolant? 50/50? Same question for the shop that did your flush. I have seen noticeable reductions on antique vehicles with non-pressurized cooling systems from adding Water Wetter, YMMV.

I have a Bostig, my ultragauge is set to alarm if CHT goes above 235 and on particularly long/hard climbs I have hit 240. As long as you are not seeing 240+ on the regular I would not sweat it, and just burp any remaining air every once in a while.
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Grant
In the stable: 1986 Syncro Westfalia/Bostig, 1989 Doka Tristar, 1974 Vespa Rally 200, 1973 Vespa Primavera 125, 1963 Solex 2200, 1938 Buick Special
Gone but not forgotten: 1989 Porsche 944, 1973 Standard Beetle

[dogmandlux]

I'm seeing the CHT on an ultragauge and thats really the only temp reading I have except the stock gauge which is kind of arbitrary I guess.

When I lost coolant, I replaced it with 50/50, and then I had a shop do a flush, and they used 50/50 as well. I got quite a bit of air out of the system after they flushed and 'burped it', apparently not very well.

On the highway I'm seeing CHT's that look pretty good to me, 205-215. Its in the stop and go that the coolant gets hot (2/3-3/4 of the stock gauge) and my CHT can see 230 and probably hit 240.

If the lower temp sensor would cool things off a little during stop and go, or say during extended slower dirt road driving that wouldn't be a bad thing would it? As that is when I'm seeing the temps of concern.

I could just be paranoid and have my eyes glued to that ultragauge, and nothing happened at all, it is just the result of stop and go in +20 degrees ambient temps that I've never driven in before. But I was concerned because it seemed to happen after i lost some coolant when my belt broke, which is coincidentally also when ambient temperatures rose as well getting into california.

Im going to try the temp sensor i think, and keep the other handy, as it seems easy enough to swap out. And I see some slow desert driving in baja happening in the next few weeks, so a little help staying cool wont hurt.

Thanks for all the responses.

[MarkWard]

The vanagon radiator fan has a built in safety. When temp turns fan on, the lower of the two speeds is active. If that speed is not able to maintain temp and it continues to climb, the faster second speed kicks in. If you are not
getting into the second speed, I wouldn’t be concerned.

My engine coolant in hot ambient is 190f. Climbing Pikes Peak I got into the second rad fan speed. Other than that, maybe at a light getting off the highway I hear it.

An explanation of cylinder head temp would be helpful. A cast aluminum head is going to absorb more heat than just coolant. Figure EGT is probably 1200 F or more in the exhaust port and combustion chamber.

My ECU reads actual coolant temp. A hot cylinder head won’t cool as quickly as circulating coolant.
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[dogmandlux]

Yeah I really need to see some coolant temps to know whats really happening. Seeing the Head temp fluctuate all over can cause some serious anxiety haha. Its a curse of the ultragauge.

Any idea what ideal coolant temps are? I guess assuming the fan kicks on at 200, right below that would be around ideal.

Thanks gentleman.

[kourt]

My Bostig runs at 180 coolant temp, measured by the sensor at the thermostat housing and reported on my gauge. On hot days, or going up Pikes Peak, I might get to 200, but it's always regulated and the radiator fan kicks in automatically.

My gauges are a Speedhut conversion (see here for more info), so I have calibrated temp gauges for reporting coolant temp, oil pressure, voltage, and a GPS speedometer. Imagine that--actually useful gauges!

kourt

[SyncroButter]

Possible I am mistaken, but I am pretty sure that my Bostig and ultragauge II setup gives me both CHT and coolant temp. May want to check in your ultragauge setup to see if you have this as well.
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Grant
In the stable: 1986 Syncro Westfalia/Bostig, 1989 Doka Tristar, 1974 Vespa Rally 200, 1973 Vespa Primavera 125, 1963 Solex 2200, 1938 Buick Special
Gone but not forgotten: 1989 Porsche 944, 1973 Standard Beetle

[dogmandlux]

Okay fellas ( the few of you who responded) (so appreciated)

Currently in Punta San Isidro, Baja California Norte. Drove 6-7 hours today in Mex. Highway speeds CHT pretty stead at 220. When we slowed down to crawl over a dirt road with incline or stop and go the temps would rise to 230-240, and would fall as soon as I got going again.

Im going to stop worrying about the temps and just jam on this trip. Ive had my eyes glued to the ultraguage for a few days and its was just driving me nuts just watching the fluctuation.

picked up a lower temp fan thermoswitch, just as a specific question, does anyone think its actually a bad idea to install for the slow crawl out some dirt roads here in baja? Stock coolant guage is just below LED at full highway speeds, and when I'm driving real slow in traffic or dirt roads, its climbs to 3/4. Is there any reason if the fan kicked on a little earlier, this would be bad? I wouldn't really mind it just for psychological reasons haha.

Thanks for the help and cheers

[jimf909]

[TopBud]

I also have a bostig that runs "hot." I installed it over the summer and was in touch with Jim a bunch. On several big dirt climbs, I saw temps of 235. Upon Jim's recommendations I set my alarm at 240 and run it. I can let off the pedal and the temps drop quickly. That is what you are looking for. After my install I did another coolant flush upon many suggestions and it really didn't help. I just replaced my front blower fan and front heater core. I have been driving locally and haven't had the time to test it with the new heater core.
I had time today and it was about 215. 7000-8000 feet altitude at speeds between 70 and 75. I did the test run without looking at my coolant level, I will check it in the morning, but I believe that this system will burp itself.
There is also a bostig owners group on FB. I posted there throughout this whole "hot issue"
.
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86 bostig SYNCRO
66 convertible Karmann Ghia

[dogmandlux]

[jocoman]

My Bostig rig is pretty much as the OP describes it. I have put a manual switch in to turn on the medium or high speed cooling fan as required.
As I only see higher temps in stop and go in summer, I will anticipate the situation and flip on the fan manually to stem the rise of temperature.
Its a new rad and I do not believe there is anything wrong with it. BTW I don't think i trust the stock temperature gauge. I would prefer a better water temperature gauge and may install one at some point to really know what is going on with coolant temps.
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'86 Westfalia 2.0L Zetec
'97 Volvo 850 AWD Turbo
" The fun never stops"

[Farfromslow]

I had a customer with high Bostig temps and after many a search and bleed we figured out it had an incorrectly boxed thermostat, after replacement the temps were fine. Check your part numbers, sometimes even new parts aren’t what there boxed up to be

[dogmandlux]

Just an update for anyone concerned, Installed the lower temp Rad fan swtich, and when i pulled the old one, I'm pretty sure that it wasnt the stock switch, and was the higher temp version, so maybe my fan wasnt kicking on soon enough.

however with the lower temp switch install, my coolant temps (based on the stock gauge, so taken with a grain or two) has been solid below the LED not really budging. When we are driving off road down here in Baja with prolonged uphill stretched in first gear, the coolant temp doesnt shoot up anymore which I do like. The only concern i have is I cant tell if the fan is coming on when cruising at about 35-40, when its not really needed.

Pretty sure its staying off during highway crusing because the coolant temp drops a little with added airflow of high speeds.

thanks for the responses
happy travels.

[MarkWard]

Temporarily rig a 12 volt testlight so you can see the fan turn on and off.
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[pnocean]

Been reading many threads on Bostig CHT on The Samba, the Bostig FB group and the Focus Fanatics Forum.

My 1987 2WD Westy was converted to a Zetec in June and the numbers mentioned on this thread correspond to what I am getting. The engine I have has 49K miles on it and it was from a totaled Focus in 2004. It sat on a shelf in a warehouse at the yard and I believe the block had some corrosion in it (Bostig Jim actually came up with this theory.) We were seeing heat build as everything warmed up and it would stay in the 235-245 range. Jim suggested a Thermocure additive treatment. I am currently on a week into driving the bus with the thermostat removed and 2 quarts of thermocure in the coolant system. My radiator was replaced 12 years ago and I have the GoWesty SS coolant lines back to front.

The temps have been dropping and I've daily driven the bus and had a 4-hour (2 hours out and back) trip on major highways where I averaged 217 - 219 CHT in 85F ambient temps and just did on today (70 miles) at 82F where I really pushed it up hills and hit 70/75 MPH. Saw a brief high of 228 on a long hill and then dropped down to 221. Temps immediately dropped when I hit off ramps to 205 and often went under 200 to 197.

I also am running a manual low-speed/high-speed fan switch and this does make a difference. In fact, when leaving for a 2-hour drive in 90F last weekend, I hit some stop-and-go and was dismayed to see CHT rising to 235 and going up. Realized I forgot all about the fan switch! Once I hit the low speed, CHT came down to 215 and averaged that back on the highway all the way home.

This appears to verify other posts on this thread about higher CHT temps in stop-and-go traffic with no fan.

We are hoping to dial in and take off for two week trip to Wisconsin, then up to the UP of Michigan and south to a music festival the next week. Lots of driving!
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'87 Westy "JoesVan"