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 Andy
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Andy's Adventures
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| posted on June 1st, 2003 at 10:41 PM |
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Kombi oil and Cyl head temperature
Kombi Cooling Test Results.
First things first. Andy is a ’77 dual carb 2L motor + GB, all stock with mineral oil in engine and GB. Another point worth noting is I have
215/75R15 tyres on, so the engine runs a little slower than normal ~9%.
It has ALL tinware and an operational thermostat. It’s getting a little tired now, ~118psi compression on all cylinders, and is in need of new
bearings. It also runs a little rich at the moment.
I have all VDO gauges less than 6 months old.
So, onto the test. Ambient temp 14degC for morning start up.
Idle time 5 min, by which time Cylinder head temp is at 65degC, oil temp doesn’t register (it starts at 50degC)
Drive 5min. through suburban streets, CHT up to 90, oil still doesn’t register.
Onto the highway at 80km/hr for 5 min. CHT up to 120, oil just over 50.
Speed up to 100km/hr for a further 5 min. CHT has reached steady state at 135. Oil up to 80. It takes just over 10 min. more for the oil to reach a
steady state of 100degC.
I then open the engine hatch and run for a further 15min at 100km/hr. NO CHANGE. CHT remains at 135, oil at 100.
Afternoon run. Ambient temp 24degC.
Idle time 1 min, by which time Cylinder head temp doesn’t register 40degC minimum on gauge, oil temp doesn’t register.
Drive 5min. through suburban streets, CHT up to 85, oil still doesn’t register.
Onto the highway at 80km/hr for 5 min. CHT up to 120, oil ~60.
Speed up to 100km/hr for a further 5 min. CHT has reached steady state at 135. Oil up to 90. It takes just over 10 min. more for the oil to reach a
steady state of 105degC.
I then open the engine hatch and run for a further 20min at 100km/hr. NO CHANGE. CHT remains at 135, oil at 105.
So, there you have it. Opening the rear hatch made no difference for my test.
I will add results without the thermostat connected when time permits.
Just a few further observations regarding cooling.
When I come off the highway and back to suburban streets, the CHT quickly drops to 120. The oil only drops ~5deg VERY slowly.
CHT varies fairly quickly with load (ie foot to the floor driving, vacuum gauge at zero increases temp). Oil varies slow with RPM, higher RPM
increases temp.
On a recent trip to Adelaide and through the Flinders, with daily temps up to 45deg. The CHT occasionally reached 180, but backing off kept it below
that. I struggled with oil temps up to and just over 130. The only way to keep it down was to take a break every 20 min or so. Consequently I did two
oil changes on the 6000km trip.
:thumb
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kombikim
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| posted on June 2nd, 2003 at 08:06 AM |
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very thorough, thanks for doing this for us Richard, it is great to have accurate data like this |
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Andy
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| posted on June 2nd, 2003 at 08:41 AM |
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clarification
Just to clarify one point already asked, the CHT sender is under the No 3 spark plug. It is also the one gauge I have not checked for accuracy, and
does seem lower than 'normal'. Will try to check soon.
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Nitram_Ztilad
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| posted on June 2nd, 2003 at 12:35 PM |
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Andy,
I'm keen to know about the temp. measuring gear you are using. I have a digital temp gague that I bought from Jaycar for about $100. It came
with a couple of sensors, which are not suitable for under-plug application. What are you using for the underplug thermocouple ? Where do I get one
from ?
Thanks for your help.
Nitram
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pyr0
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| posted on June 2nd, 2003 at 12:46 PM |
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great work that post alone settled a big discussion me and a couple of my mates were having. thanks for the accurate info |
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Andy
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| posted on June 2nd, 2003 at 01:01 PM |
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Well, it's a bit sad when you have to prove yourself wrong 
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Nitram_Ztilad
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| posted on June 2nd, 2003 at 01:47 PM |
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So where can we get a thermocouple ?
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mnsKmobi
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| posted on June 3rd, 2003 at 04:04 PM |
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| Quote: | Originally
posted by Nitram_Ztilad
So where can we get a thermocouple ?
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The thermocouple Andy refers to comes with the VDO CHT gauge.
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Andy
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| posted on June 3rd, 2003 at 04:11 PM |
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Yes, thanks mnsKmobi.
Nitram_Ztilad, I missed the question. It is best to buy them as a set, as they are calibrated from the factory, thermo couple, cable and gauge.
They are very sensitive, and you shouldn't alter the wire lenghts.
People do shorten/lengthen them, but it does affect the reading slightly.
Andy :thumb
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Robo
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| posted on June 3rd, 2003 at 04:26 PM |
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Hi Andy
How dose the thermo coupler mate to the head, do you need to machine a thread, or dose it go between the plug and the head.
So when you buy the kit, you tell them it is for a kombi and they give you the right length wires, and other stuff, or you have to do it your self,
I realise it may be a dumb question, but if you dont ask
Do you have a gauge for each head, or is one sufficient.
Rob.....
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70AutoStik
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| posted on June 3rd, 2003 at 08:17 PM |
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The VDO sensor has the thermocouple imbedded in a copper lug which is placed under the exhaust nut. Many years ago another type was available, which
involved having a small hole drilled and tapped into the exhaust flange on the head. One sensor is sufficient, it is usually mounted on No 3
cylinder, as this tends to run the hottest.
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Andy
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| posted on June 3rd, 2003 at 10:08 PM |
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Robo,
Further to what 70AutoStik said, my VDO thermocouple replaces the washer on the spark plug, so yes, it's between the plug and the head.
As 70AutoStik said, No 3 tends to run the hotest, so that's the place to put it.
From memory the kits come in two lenghts of wire, and the longer one is only just enough, so you have to run the wires as straight through as you
can.
:thumb
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Robo
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| posted on June 4th, 2003 at 04:21 PM |
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Thanks Andy.
I have been putting off adding this gauge because I thought you had to have a sender port machined into the head, looks like the spark plug idea, is
a strait forward instilation.
BTW, heading off to the Sapphire this weekend, the wife and kids are tagging along in the Kombi.
Rob.......
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KruizinKombi
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| posted on June 4th, 2003 at 04:45 PM |
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Andy, how thick is the thermocouple under the spark plug? Do you use a longer plug to compensate?
Can someone give me an idea of how much the various units cost? I'm preparing to put a fully reco'd motor in my kombi and I'd like to
be able to keep an eye on it.
Kruizin Kol
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Purple Martin
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| posted on June 4th, 2003 at 04:47 PM |
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Thanks for the figures Andy.
It sounds like you've got a lot of guages - can we have a pic of your dash please?
1959 red & white Beetle
1975 Kombi camper
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Andy
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Andy's Adventures
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| posted on June 4th, 2003 at 05:18 PM |
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Kruizinkombi, the thermocouple REPLACES the normal spark plug washer, so depth in head remains the same.
Rough prices from my failing memory, most gauges ~$40ea, senders, ~$40ea, CHT kit ~$130. All VDO. It was a reasonable deal getting them all in one
hit. Only the CHT is imperial, hate that crap.
Robo,
have a look here
http://www.aussieveedubbers.com/forum/viewthread.php?tid=4445
Not the best of pics, but gives you the idea.
Soon to be fixed is a proper clock (small VDO one currently).
Admittedly I went gauge mad, but I though what the hell. 
I my opinion a well maintained and conservatively driven VW doesn't need any gauges. If you like to prevent any potential damage in harsh
conditions I would recommend just a CHT and oil pressure
Any others are not necessary.
:thumb
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Robo
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| posted on June 4th, 2003 at 07:06 PM |
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Cool Bananas, now I know what I want for fathers day!
Rob....
Boxer Power
Member of DMLRK.....Die Mittler Lebuns Resto Komeradschaft
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KruizinKombi
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| posted on June 5th, 2003 at 11:03 PM |
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Sounds great, but I'm not sure I'll be able to afford gauges before Nambucca.
Kruizin Kol
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