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Post by busaddict on Jun 2, 2022 20:23:25 GMT -8
Checked the compression on my '73 bus this afternoon and found these readings. Poured some motor oil in number 2 cylinder with no improvement (only 30 PSI.) I suspect this is a valve issue, possibly number 2 exhaust. Take a look at the photo, number 2 on the far left looks like it may have heated up. The bus drives fairly smoothly but rocks a little at idle. Any suggestions welcome, I imagine I'll have to rebuild or replace both heads to do a proper job. This vehicle sat off and on over the years and only has about 150,000 miles on the clock so perhaps only a top end rebuild.
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Post by Volktales on Jun 2, 2022 21:59:15 GMT -8
Did you try adjusting it first? Any clearance there? Over the years most of the low compression issues I have seen in those is due to a failed valve seat or valve itself burning out...
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Post by 1hotvw on Jun 2, 2022 22:05:44 GMT -8
you may have a loose seat ready to drop, common on these motors. don't run, at risk of engine genadeing. if you replace heads have a shop peen the seats.i think even replacement heads are not peened. vw did this on type 1s but not on these motors.
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Post by busaddict on Jun 2, 2022 22:13:00 GMT -8
Did you try adjusting it first? Any clearance there? Over the years most of the low compression issues I have seen in those is due to a failed valve seat or valve itself burning out... Before the compression test I adjusted the valves (.006 intake and exhaust) and everything looked good to me, but the rough idle persisted. I re-checked the valves on number 2 after the compression check and re-did the test on number 2 with the same 30 PSI result. So if it is a failed valve seat or burned out valve is there a relatively "easy" way to fix it? I'm not sure I should be driving it in this state. As always, thank you for your advice  |
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Post by busaddict on Jun 2, 2022 23:04:11 GMT -8
you may have a loose seat ready to drop, common on these motors. don't run, at risk of engine genadeing. if you replace heads have a shop peen the seats.i think even replacement heads are not peened. vw did this on type 1s but not on these motors. I think to do it properly I'll need a shop to do both heads. Thank you for the tips. Looking at the Busdepot, they often have good deals (depending on the exchange rate) Prices have certainly gone up, and this is in American dollars for 1 side. www.busdepot.com/022101361k |
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Post by Volktales on Jun 3, 2022 11:18:47 GMT -8
Exhaust valves are set to 0.008" on type 4 heads, intakes 0.006".
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Post by busaddict on Jun 3, 2022 12:54:42 GMT -8
Exhaust valves are set to 0.008" on type 4 heads, intakes 0.006". I thought that was only if they were 1974 with sodium filled exhaust valves. However, that said, I previously had been setting the exhaust at .008  |
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