All You CHT Gauge Drivers Report Here

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SlowLane
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Re: All You CHT Gauge Drivers Report Here

Post by SlowLane » Sat Jun 06, 2015 10:09 am

After having my van sit in the driveway and look accusingly at me for the last three years, I finally got motivated to once again tackle the process of getting it legal to drive in California. The people at the DMV were surprisingly helpful, issuing me a sequence of temporary passes which allowed me to drive it around while getting ready for smogging and registration.

When I first started drive it around, I noticed a peculiar pattern on the quad-channel CHT gauge that I hadn't seen before. Previously, cylinders 1 & 3 would track each other fairly closely, staying within a few degrees of each other, while cylinders 2 & 4 would also track together, but typically 20-40 degrees lower than 1 & 3.

What I was now seeing was that cylinder 1 was getting a lot hotter than any of the others, and cylinder 4 was a lot cooler. On one reading, cylinder 1 was at 361, 2 & 3 were at about 310, and cylinder 4 was at 270. Nearly 100 degrees difference between the hottest and coldest cylinder. So I gingerly drove back home, ready to start tearing the engine apart, but by the time I did get home, the temperatures had evened out to their normal distribution. WTF?

Then it hit me: the difference between now and back then was that I had installed a working Awesome thermostat in the interim. The weird new pattern I was seeing was because the thermostat hadn't opened up yet, but by the time I got back home it had, so things were back to normal. I don't have a good explanation as to why the left half of the engine was getting more cooling than the right half with the thermostat closed, but now I just take it easy during the warm-up phase to keep cylinder 1 from getting too far whead of the rest.

So that peculiarity is solved. Then yesterday I observed another one. I took a trip out to the DMV in Tracy to get my registration paperwork completed, going though the Altamont Pass. Well, the Altamont Pass is pretty windy: that's why they put up all those windmills there. The trip out with a tailwind was very pleasant, but coming back into that headwind was a real trial. My #3 cylinder hit 400 degrees while limping along at 50 MPH on the flats, and climbed to 410 when climbing the gentle grade up to the pass itself. In the meantime, cylinder 1 was at a comfortable 365 the whole time.

Now I know from spark plug inspection that #3 runs lean, while #1 & 2 have perfect coloration (#4 seems to have an oil consumption problem, as it's always oily-black). I have my suspicions that #3 is starved for fuel because it's the last cylinder in the fuel rail and therefore would have the lowest fuel pressure of all four cylinders. I'm planning to do some measurements to back up or refute this theory, and probably will implement a dual-loop system similar to that used on the wasseboxers in the later Vanagons.

Of course, I will first make sure that I don't have any lurking vacuum leaks on the #3 cylinder intake. :wink:
'81 Canadian Westfalia (2.0L, manual), now Californiated

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Re: All You CHT Gauge Drivers Report Here

Post by Boxcar » Sat Jun 06, 2015 4:14 pm

Thermostat is a great part to renew.

Keep us posted on the dual loop mods.

Thanks// eric
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Re: All You CHT Gauge Drivers Report Here

Post by Amskeptic » Tue Jun 09, 2015 6:05 am

SlowLane wrote: The weird new pattern I was seeing was because the thermostat hadn't opened up yet, but by the time I got back home it had, so things were back to normal. I don't have a good explanation as to why the left half of the engine was getting more cooling than the right half with the thermostat closed,

Headwind was a real trial. My #3 cylinder hit 400 degrees while limping along at 50 MPH on the flats, and climbed to 410 when climbing the gentle grade up to the pass itself. In the meantime, cylinder 1 was at a comfortable 365 the whole time.

Now I know from spark plug inspection that #3 runs lean, while #1 & 2 have perfect coloration (#4 seems to have an oil consumption problem, as it's always oily-black).
Flaps can be and should be adjusted for equal function. You can twist the cross shaft to make them equal. The right side has to "leak" when cold so that air gets to the thermostat to open it.
400* is not worthy of "limping". Get your foot in it and be happy that occasional hot operation cleans the carbon off the valves and exhaust. I am set for 430* flash on the BobD, and 420* on Chloe. I have hit those numbers on uphill headwinds twice in Chloe (423* the day before yesterday) and said "deal with it, it is raining too hard for me to care." Engine didn't care.

Please consider the fact that #3 is not necessarily "leaner" but will show evidence of working harder than 4 based on heat generated by that work. That is why we want consistent output from all cylinders thus more equal evidence of operating temps before blaming injector variances etc. So why is 4 loafing? Oil consumption and lower compression, or just oil consumption? I would be happy to run # 4 a little hotter to keep the carbon down. Do you have a hotter plug you could install in #4 only?
Colin
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SlowLane
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Re: All You CHT Gauge Drivers Report Here

Post by SlowLane » Wed Jun 10, 2015 10:07 am

Colin wrote:Flaps can be and should be adjusted for equal function. You can twist the cross shaft to make them equal. The right side has to "leak" when cold so that air gets to the thermostat to open it.
Thanks. Got any suggestions for how to twist the cross-shaft without removing the fan housing? Pair of vice-grips?
Colin also wrote:400* is not worthy of "limping". Get your foot in it and be happy that occasional hot operation cleans the carbon off the valves and exhaust. I am set for 430* flash on the BobD, and 420* on Chloe. I have hit those numbers on uphill headwinds twice in Chloe (423* the day before yesterday) and said "deal with it, it is raining too hard for me to care." Engine didn't care.
Yer a braver man than I am, Gunga-Din. But having had two previous engines drop valve seats on me has made me a little gun-shy, so I have my warning start to flash at 390 F. Just want to be clear that "getting my foot in it" didn't help. It could still barely manage 50 MPH into that headwind.
Colin further wrote:Please consider the fact that #3 is not necessarily "leaner" but will show evidence of working harder than 4 based on heat generated by that work. That is why we want consistent output from all cylinders thus more equal evidence of operating temps before blaming injector variances etc. So why is 4 loafing? Oil consumption and lower compression, or just oil consumption? I would be happy to run # 4 a little hotter to keep the carbon down. Do you have a hotter plug you could install in #4 only?
I do have a new set of Bosch WR8 plugs, which are hotter than the WR7 plugs which are in there right now. I was leery of mixing in different heat range plugs, but I'll give it a shot. #4 isn't that badly fouled, but it definitely has an oily appearance that the other three don't, which seems to have been the case since I rebuilt the engine, so I suspect that I have a ring seating problem on that cylinder.

Last time I did a compression check I had great even compression on all four cylinders, but that was back in Canada before I drove her down here. The van has been sitting dormant for nearly three years, so it's possible that I had rusty cylinder walls when I fired her up again last month. I'll do another compression check to make sure.
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Re: All You CHT Gauge Drivers Report Here

Post by 72Hardtop » Mon Jun 15, 2015 12:15 am

Junk the Bosch plugs and pony up for some NGK B5ES plugs. Bosch plugs are no longer made in Germany and the quality has suffered as a result. The NGK plugs are top notch and you quickly see out of the box when compared to the Bosch.
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SlowLane
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Re: All You CHT Gauge Drivers Report Here

Post by SlowLane » Mon Jun 15, 2015 1:33 pm

72Hardtop wrote:Junk the Bosch plugs and pony up for some NGK B5ES plugs. Bosch plugs are no longer made in Germany and the quality has suffered as a result. The NGK plugs are top notch and you quickly see out of the box when compared to the Bosch.
Thanks, but I don't think the plugs are the problem here. I actually did have a set of the NGK triple-electrode plugs in this engine at one point. They worked okay, No noticeable difference in performance over the Bosch copper plugs I normally use. The NGKs had the same coloration pattern that I noted on the Bosch's: 1 & 2 were perfect, 3 looked lean and 4 looked blackish/oily.

Having said that, I have had some faulty Bosch plugs in the past. Most alarming were the plugs where the ceramic body was a loose fit in the metal part of the plug: I could actually spin the ceramic part around inside the metal part. Needless to say those went back to the store for an exchange.
'81 Canadian Westfalia (2.0L, manual), now Californiated

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Re: All You CHT Gauge Drivers Report Here

Post by Amskeptic » Fri Jun 19, 2015 9:13 pm

SlowLane wrote:
72Hardtop wrote:Junk the Bosch plugs and pony up for some NGK B5ES plugs. Bosch plugs are no longer made in Germany and the quality has suffered as a result. The NGK plugs are top notch and you quickly see out of the box when compared to the Bosch.
Thanks, but I don't think the plugs are the problem here. I actually did have a set of the NGK triple-electrode plugs in this engine at one point. They worked okay, No noticeable difference in performance over the Bosch copper plugs I normally use. The NGKs had the same coloration pattern that I noted on the Bosch's: 1 & 2 were perfect, 3 looked lean and 4 looked blackish/oily.

Having said that, I have had some faulty Bosch plugs in the past. Most alarming were the plugs where the ceramic body was a loose fit in the metal part of the plug: I could actually spin the ceramic part around inside the metal part. Needless to say those went back to the store for an exchange.
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Chloe - 70 bus . . . 217,593 miles
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Re: All You CHT Gauge Drivers Report Here

Post by Na Nook » Tue Mar 15, 2016 6:52 pm

Took my first major trip up a grade today started at 1600FT above sea level, 11 miles later, 5,970FT above sea level. The road is very curvy with many switchbacks. The engine had been performing very well with CHT never exceeding 402F during a 65+ MPH run. During this steep climb in 3rd gear, maintaining a consistent 3200 RPM, the CHT never exceeded 397F, with an average between 378F +- 10F. The setup is an 1800cc, solid lifter, progressive carb, with a Dakota Digital gauge. Here are some pics for ya'll.

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Re: All You CHT Gauge Drivers Report Here

Post by Trexco » Tue Mar 15, 2016 7:35 pm

Hi Amskeptic, Just installed a new set of Len Hoffman heads on my 82 Westfalia. I am having a cht issue that I am trying to chase down. I have spent a fair amount of time sealing all of the areas around the engine and made sure that the timing and points are set correctly timing is at 7.5 btdc and points are at 48* dwell. Temps are running around 410 at 60mph and 80 degrees ambient on level ground. The vehicle has 16 inch wheels. One big concern that I have is that some po has replaced the vacuum advance distributor with a centrifugal one. The van has stock FI. I would like to be able to run this at 65mph or better, but temps start creeping up around 420 and have hit 430 on brief hill climbs around Dade City area on I75 in Fl. New thermostat installed flaps appear to be working correctly. Temp readings are from a Dakota Digital gauge. I did have Lynn machine the heads for the DD gauge. Engine feels pretty strong cylinder pressures between 110 and 120 on all 4. Got 16mpg on last trip (300 miles). I have done a smoke test and fixed all of the vacuum leaks that have shown up ... What would you try next ?
1982 Westfalia 2.0L AC running 16in tires with Dakota digital cht. Stock FI

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Re: All You CHT Gauge Drivers Report Here

Post by asiab3 » Tue Mar 15, 2016 9:34 pm

Hi Trexco, and welcome! Thanks for a detail-oriented first post.

The first thing I would check it where your timing falls with your mechanical advance only distributor. 7.5*btdc worked fine with new Volkswagen parts 30 years ago, but now we have to be cautious when swapping things around. Do you have a strobe timing light? Can you set the timing to a verifiable 28*btdc when you've revved the engine up until the distributor stops advancing? (This usually happens around 3,200-3,600 RPM.)

We set the timing this way, because we want to be in the "safe zone" when the engine is asked to work it's hardest. Since we don't drive around at idle all day, we pay attention to where the idle (and static) timing marks fall, but we don't adjust for them.

If you check your max advance timing and it's far advanced, you may have found the issue. Because this is a free and relatively easy check, it's nice to start with.

Once we've confirmed your timing at maximum advance, we'll go through more checks and details to get to the bottom of your temperatures.

Let us know if you have any questions, or need help with the timing procedures.

Have fun,
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Re: All You CHT Gauge Drivers Report Here

Post by Bleyseng » Wed Mar 16, 2016 7:35 am

Check your Air Fuel Ratio after resetting the timing as you could be running lean too. What is your CR?
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Re: All You CHT Gauge Drivers Report Here

Post by airkooledchris » Wed Mar 16, 2016 7:52 am

what RPM are you at when you report these CHT's? - this is more important to know than the MPH you are travelling.

what size tires are you running on those 16's?

if your rpms are too low at those speeds, you may have too big of tires for the gearing of the freeway flyer style gearing the Vanagon transmission uses.
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Re: All You CHT Gauge Drivers Report Here

Post by SlowLane » Wed Mar 16, 2016 7:55 pm

Trexco wrote: One big concern that I have is that some po has replaced the vacuum advance distributor with a centrifugal one. The van has stock FI. I would like to be able to run this at 65mph or better, but temps start creeping up around 420 and have hit 430 on brief hill climbs ... What would you try next ?
Do your engine a huge favour and get a freshly cleaned-and-lubed vacuum advance distributor in there. L-jet came with one and deserves one. Do you have a federal- emissions Vanagon or a California- emissions one?

Suggest you drop your dreams of running at 65 or better. These vehicles just aren't built for maintaining those kind of speeds for any length of time, as is reflected in the head temps you are seeing when you try.

Then again, since your heads have been given the Len Hoffman treatment, you don't need to be as worried about those kind of head temperatures as do we with lesser heads.

Just my $.02
'81 Canadian Westfalia (2.0L, manual), now Californiated

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Re: All You CHT Gauge Drivers Report Here

Post by airkooledchris » Wed Mar 16, 2016 8:46 pm

SlowLane wrote:
Trexco wrote: One big concern that I have is that some po has replaced the vacuum advance distributor with a centrifugal one. The van has stock FI. I would like to be able to run this at 65mph or better, but temps start creeping up around 420 and have hit 430 on brief hill climbs ... What would you try next ?
Do your engine a huge favour and get a freshly cleaned-and-lubed vacuum advance distributor in there. L-jet came with one and deserves one. Do you have a federal- emissions Vanagon or a California- emissions one?

Suggest you drop your dreams of running at 65 or better. These vehicles just aren't built for maintaining those kind of speeds for any length of time, as is reflected in the head temps you are seeing when you try.

Then again, since your heads have been given the Len Hoffman treatment, you don't need to be as worried about those kind of head temperatures as do we with lesser heads.

Just my $.02

amazing heads, yes, but a fresh cam to compliment them would be the *ideal* scenario for running carefree highway speeds on the regular.
1979 California Transporter

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Re: All You CHT Gauge Drivers Report Here

Post by Trexco » Wed Mar 16, 2016 9:44 pm

Hello, follow up information. Timing appears to be about 27*btdc at 3200. Sorry the vehicle is a federal (I think) there is no Halls unit (although the side has holes were one might have mounted at one time) but it does have points. There is also a steel line that comes off the side of the throttle body that comes back to the sheet metal on the drivers side and is blanked off with a flange. It appears to be thermally activated open at cold temps and closed once engine heats up (old EGR line I think). It was a source of vacuum leaks when the engine was cold until I properly blanked it off. PO had not used a gasket just a flat plate. PPO had an engine fire and replaced things that were too badly singed so not sure if engine is original or not. PO did not do too much with it, although they cut a 6 inch by 8 inch hole in the tin for an after market air conditioner compressor to clear. I removed that and patched the sheet metal. The tires are 215 R6016. The odometer is off by about 13% according to my gps. Odometer reads 87 miles when GPS says 100. Speedometer is about three miles lower than actual by GPS speed.

Yes I would like to replace the distributor with a vacuum advance tried to do it once before but the drive was different. The centrifugal one has the drive notch off center where the new distributor appears to be centered on the drive bar. I realize these are not a speed demon, but I would think that I should be able to get 60-65 on level ground and stay under 400 on cht. I read on here several people that have achieved this, and are running 70. Had a 78 or 79 yellow vw westfalia blow by me on the interstate Sunday when I was running 60. Admittedly I don't know what engine he was running but it was impressive.

Sorry not sure what CR stands for, I am assuming that it has to do with fuel mixture. No Tach mounted in cab so unsure about rpms on the road. I usually shift 3rd to 4th around 50mph as third is pretty much wound out by then if that gives any indication. Have a handheld meter that reads rpm when working on engine.

I need to get some additional instrumentation, EGT and Oil Temp is on my list ... Just waiting for funds to accumulate.
Thanks for all the suggestions ...
1982 Westfalia 2.0L AC running 16in tires with Dakota digital cht. Stock FI

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