Rising oil temps on 83 air cooled

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Rising oil temps on 83 air cooled

Post by 83AC » Tue May 23, 2017 3:05 pm

We recently had our engine rebuilt after learning of a melted piston on cylinder 1, and also had a vdo oil temp gauge installed with the sensor in the taco plate. During our 500 mile break in, running in early spring cool to cold temps up to about 50 to 55 mph, oil temp read about 200 to 220*. Once we got it back after the 500 mile check up, the oil temps ran somewhat higher, still in 40 to 60* weather - averaging 220 or slightly higher at highway speeds. We are currently in Nelson, B.C. On a long and winding trip cross country (about 2000 miles in since the last check up and oil change) and temps the last few days have climbed into the 80s, while our oil temps have been reading, at cruising 50 to 55, about 240 to 250* after the initial warming up of 30 to 45 minutes. The temps have seemed to stay around 240 to250* whether uphill, downhill, or flat. I have not adjusted anything yet or delved in too deeply. I made sure the thermostat heat flaps are working correctly and they are. Was thinking of checking the temp 2 sender for correct readings, but beyond there am getting a little nervous . . . Not sure I need to be. I'd love some insights. In Nelson a few days then off toward Banff and back south into the states.
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Randy in Maine
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Re: Rising oil temps on 83 air cooled

Post by Randy in Maine » Wed May 24, 2017 4:39 am

What is this engine timed at?

Oil viscosity?

Are you above 5000' in elevation? If so you might a degree or so of more timing.
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Re: Rising oil temps on 83 air cooled

Post by 83AC » Wed May 24, 2017 8:33 am

Randy I haven't checked the timing personally, but I believe when they rebuilt the engine they set it as close to stock as possible. We have only briefly been above 5000 feet on the trip and are currently around 2200. Oil is 20W50.
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Randy in Maine
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Re: Rising oil temps on 83 air cooled

Post by Randy in Maine » Wed May 24, 2017 10:04 am

My experience was that retarded timing really helped to generat high oil temps.
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Re: Rising oil temps on 83 air cooled

Post by 83AC » Wed May 24, 2017 9:58 pm

Well we can now add a symptom: oxygen sensor light came on today. I don't have a CO reader so will try to get in touch with a shop here in Nelson and see if they can help us out. Was a really light day of driving - top speeds of 50mph and total drive time of about 40 minutes then several hour rest then 20 minutes, when the sensor came on, then another hour or so rest, then hour drive home. No issues with driveability, just going to research oxygen sensor stuff now . . . Bah.
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Re: Rising oil temps on 83 air cooled

Post by Randy in Maine » Thu May 25, 2017 4:43 am

I am pretty sure the O2 sensor light just comes on with mileage like every 30K miles or something. There is likely a reset button on it someplace, but I think that is a "red herring".

If it were me, I wold find a timing light to own and would observe the timing advance and retard as the engine speed changes to make sure you are getting the timing advance you desire. Make sure the vacuum cans are not leaking and are actually moving the distributor innerds.
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Re: Rising oil temps on 83 air cooled

Post by Randy in Maine » Thu May 25, 2017 7:58 am

And the other thing I would do would be to construct that little "smoke machine" made out of a one gallon paint can and hook that into the vacuum system to see if you are having some sort of vacuum leakage that you don't even know about. For about $10 and some time it may shed some light on just how tight your whole system is.
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Re: Rising oil temps on 83 air cooled

Post by 83AC » Thu May 25, 2017 10:39 am

Updates - OXS reset no worries. Took Penny to Lee's Auto Haus in Nelson, B.C. (Very nice guys who accommodated us quickly and kindly, and let me work alongside them to run some diagnostics and trouble shoot) where we checked the timing and advance - timing was right on and advance was 44 at about 2500 rpm. That all looked good, engine sounds good, put an infrared gun on the oil temp sensor and it reads true (good to know). We weren't able to run a CO sensor to see how the ratio is, and we did not check vacuum. I'll check vacuum using the spray a little carb cleaner when we are starting our day in the next few days while the engine is cool. We acknowledged that we have been at different elevations, and that it is a rebuilt engine, which would be tighter and thus run warmer . . . So for now, we are saying things look pretty good . . . Knock on wood. I'll let you know what I find when I get around to the vacuum testing.
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Re: Rising oil temps on 83 air cooled

Post by sgkent » Thu May 25, 2017 11:11 am

You pull all the vacuum hoses off the distributor and plug them. Then you check the timing at what we call full in - which means when it stops moving somewhere around 3500 - 3800 RPM. Then the distributor gets set to 29 degrees BTDC. That is a few degrees less than factory but the delayed timing helps the engine run a tad cooler. Then you hook the hoses back up and see where it is at idle. It should be close to factory specs. If the vacuum can has two hoses then both sides have to be checked to be sure they work and that they hold a vacuum. There is USUALLY a mechanical advance on the distributor too. That way the timing will advance from about 6 BTDC at idle +/- to the 29 BTDC at 3500 - 3800 RPM and fall back quickly and smoothly at idle. There is a small felt wick under the rotor that holds a few drops of oil - 5 or 6 when the cap or rotor are changed. That oil works down into the mechanical advance mechanism and allows it to work properly. The vacuum advance consists of two plates that slide on one another. They need a little cleaning and lubrication from time to time to work smoothly.

The reason we don't time the engine with the vacuum cans on is that the timing will vary too much depending on the load. These air cooled engines are really sensitive to piston scuffing when the timing gets too far advanced.

here are the distributor specs for 1983 - scroll down to either California 1983 Vanagon or Federal 1983 Vanagon - which ever you have. The centrifugal advance does show 21 - 25 degrees at full in so if you take the mid point - 23 degrees, and add that to say 6 BTDC at idle that adds up to the 29 BTDC which is what you shooting for. If yours is 24 degrees advance then at idle it would be 5 degrees etc.

http://www.oldvolkshome.com/ignition.htm#V8083FD
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Re: Rising oil temps on 83 air cooled

Post by 83AC » Thu May 25, 2017 11:17 am

Merlin - great info . . . Tough we have left the shop and will be traveling on . . . I think I need to bite the bullet and get a timing light, huh? It seems that would make this whole thing a lot easier to keep an eye on and diagnose/set more easily . . . And cost efficiently over time. I'll see if I can convince my better half that we pick one up during our travels . . .
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Re: Rising oil temps on 83 air cooled

Post by sgkent » Thu May 25, 2017 11:51 am

Timing set improperly can burn a hole in a piston in 20 - 30 miles under load so by all means get a timing light. Look for one that has an inductive pickup. If you have the timing scale still on your Vanagon then It does not need an adjustable dial.
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Re: Rising oil temps on 83 air cooled

Post by Randy in Maine » Thu May 25, 2017 12:16 pm

The "inductive" part of a timing light is just a little gizmo that clips onto the #1 spark plug wire as close to the spark plug as you can get it. I power up the light by clamping the red and black connections to the battery or a set of jumper cables hooked up to a battery. Some lights have a "crank in the centrifical advance function" knob on the end, but if you have a timing scale you don't need that .

The light should smoothly advance and retard against the timing scale when you rev up the engine and then back off. If you need to mark that little notch on the fan, use some fingernail polish or "white out" to help you see it. The exact RPM when it is all in really doesn't matter...with the light hooked up you want to make sure that the point where it will no longer advance (hoses off) no matter how much more gas you give it is about 30º +/- 2º. I like 28º myself.

Go visit a pawn shop and see if they have something for cheap money. I have this old Sears timing light that I have had forever and paid about $70 for it new. Now it is an antique. Nobody uses them anymore but us.
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Re: Rising oil temps on 83 air cooled

Post by 83AC » Mon May 29, 2017 7:10 pm

sgkent wrote:
Thu May 25, 2017 11:11 am
You pull all the vacuum hoses off the distributor and plug them. Then you check the timing at what we call full in - which means when it stops moving somewhere around 3500 - 3800 RPM. Then the distributor gets set to 29 degrees BTDC. That is a few degrees less than factory but the delayed timing helps the engine run a tad cooler. Then you hook the hoses back up and see where it is at idle. It should be close to factory specs. If the vacuum can has two hoses then both sides have to be checked to be sure they work and that they hold a vacuum. There is USUALLY a mechanical advance on the distributor too. That way the timing will advance from about 6 BTDC at idle +/- to the 29 BTDC at 3500 - 3800 RPM and fall back quickly and smoothly at idle. There is a small felt wick under the rotor that holds a few drops of oil - 5 or 6 when the cap or rotor are changed. That oil works down into the mechanical advance mechanism and allows it to work properly. The vacuum advance consists of two plates that slide on one another. They need a little cleaning and lubrication from time to time to work smoothly.

We do have a new or refurbished distributor. I got a timing light today and we set the timing - I may revisit this again tomorrow just to be sure I have it correct, if anything, it is a little too retarded at this point. Can you tell me what effects that may cause? We don't have a tach and thus I think I could be more precise about the full in rpm if I watch he rpm increase slowly and note where it levels out to set the timing at 28 BTDC.

The reason we don't time the engine with the vacuum cans on is that the timing will vary too much depending on the load. These air cooled engines are really sensitive to piston scuffing when the timing gets too far advanced.

here are the distributor specs for 1983 - scroll down to either California 1983 Vanagon or Federal 1983 Vanagon - which ever you have. The centrifugal advance does show 21 - 25 degrees at full in so if you take the mid point - 23 degrees, and add that to say 6 BTDC at idle that adds up to the 29 BTDC which is what you shooting for. If yours is 24 degrees advance then at idle it would be 5 degrees etc.

http://www.oldvolkshome.com/ignition.htm#V8083FD
I can say that after adjusting the timing, running a long relatively flat section of road at 50mph gave me oil temps of right about 235. 45mph gave me 225 to 230. Ambient temp outside was, I estimate 75 around that time. I was able to check temp II sensor and it appears to be operating within spec. Still wondering if this is abnormal operating temperature?

Next steps will include changing the oil, revisiting timing, and possibly checking the valve adjustment (hydraulic for us).

I will keep updating and look forward to feedback. Thanks, folks!
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Re: Rising oil temps on 83 air cooled

Post by 83AC » Mon May 29, 2017 7:10 pm

In case you missed this part of my reply:

We do have a new or refurbished distributor. I got a timing light today and we set the timing - I may revisit this again tomorrow just to be sure I have it correct, if anything, it is a little too retarded at this point. Can you tell me what effects that may cause? We don't have a tach and thus I think I could be more precise about the full in rpm if I watch he rpm increase slowly and note where it levels out to set the timing at 28 BTDC.
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Re: Rising oil temps on 83 air cooled

Post by asiab3 » Tue May 30, 2017 11:48 am

I have found a slightly retarded timing setting to heat up the exhaust system (and engine compartment sheet metal) more, I think because the combustion occurs later so the heat and flames continue into the exhaust due to the combustion delay. This tricks our human meat flesh senses into thinking that the engine is running hotter, when the combustion and cylinder head temperatures are actually much lower.

There isn't a strong correlation between head temperatures and oil temperatures in my experience, so I would think about looking elsewhere once you know your timing is safe and accurate. Have you verified with another gauge? Checked for shorts in the wiring? Where is your sender located?

I shoot the case with a laser thermometer where Colin showed me, and it reads significantly higher on my bug than bus. I chased those high readings for weeks with different oils (of the snake and engine varieties) before I realized that the bus has an engine support bar between the case and the exhaust system, and the bug doesn't. :silent: So now I measure the case temp next to the distributor slot.

But I also dont care about oil temperature as long as the engine makes good pressure and the oil doesn't smell burnt.

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