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airschooled
Air-Schooled
Joined: April 04, 2012
Posts: 12722
Location: on a bike ride somewhere
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 Posted: Thu Mar 03, 2022 9:38 am Post subject: Re: compression test in type 4 |
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| Ktk833 wrote: |
Question:
What would you pick of this situation (2.0 liter type 4 engine)?
-Engine was not warm... in fact, has not run in about 2 months.
-Prior to parking, valves had been set presumably right.
-Battery fully charged
-no wet test
Tests results:
Cylinder 1: 55
Cylinder 2: 57
Cylinder 3: 60
Cylinder 4: 62.
All this are initial tests.
Rings are all new.
Also, it was my first time to do a compression test.
What I would like to know, may I far much different results if the engine was warm, if I did a wet test? Are those results way too low even for an engine in the described state?? What else may I do before I undertake subsequent tests?
Thanks. |
Put a few hundred hard miles/km on the engine before judging its compression.
Numbers drop off with elevation. This will cause low readings compared to sea level specifications.
Robbie
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Wildthings
Samba Member
Joined: March 13, 2005
Posts: 50348
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| Posted: Thu Mar 03, 2022 11:17 am Post subject: Re: compression test in type 4 |
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Since the numbers are about the same across the board, it probably has something to do with your methodology.
-Did you have the throttle held all the way open?
-Were all the plugs removed thoughout the testing?
-Was the battery well charged?
Does the engine make good power? |
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cmonSTART
Samba Member
Joined: July 15, 2014
Posts: 1915
Location: NH
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| Posted: Thu Mar 03, 2022 11:26 am Post subject: Re: compression test in type 4 |
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| Wildthings wrote: |
-Did you have the throttle held all the way open?
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This would be my first guess!
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'78 Bus 2.0FI
de K1IGS |
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JPSummers
Samba Member
Joined: July 22, 2012
Posts: 59
Location: NE OHIO
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| Posted: Sun Jul 03, 2022 12:54 pm Post subject: Re: compression test in type 4 |
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Been working on this for 3 years now. getting into the engine ("ED" 1800 FI replaced w/ a DGEV) with no history information except it was installed at 14,000 miles, Bus has 58,000 actual miles. Past registration records confirm this.
Compression Checks, Wet, Dry, Valves adjusted, all the same.
#1-95psi
#2-95psi
#3-98psi
#4-95psi
Quite low but consistent. Plugs had a LOT of carbon. It was running super rich and the fuel system was an arsonist's wet dream. Replaced the fuel system Tank to carb w/ a regulator. Rebuilt the carb which was FULL of crap, replaced the 009 Dist. w/ an SVDA, new plugs & wires. Tuning continues.
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78 Westfalia Campmobile Deluxe
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SGKent 
Samba Member
Joined: October 30, 2007
Posts: 41031
Location: Citrus Heights CA (Near Sacramento)
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| Posted: Sun Jul 03, 2022 1:05 pm Post subject: Re: compression test in type 4 |
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normal compression. Engine is cold. At 58,000 miles actual the original engine should still be almost virgin so one would wonder why the FI was abandoned for an inferior progressive carb.
Stock compression is 7.3 on buses. At sea level 14.7 (not hot, humid or low pressure overhead) X 7.3 is 107.31 PSI. The cam and cranking speed can affect it too. 107 - 98 is 9 PSI which is within 10% of what would be expected. I doubt if your gauge is a 1% precision instrument. If you are at a few thousand feet altitude, it is a hot humid day with a low pressure system overhead, I would expect the atmospheric PSI to be less. The readings you got would not concern me. |
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JPSummers
Samba Member
Joined: July 22, 2012
Posts: 59
Location: NE OHIO
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| Posted: Sun Jul 03, 2022 2:12 pm Post subject: Re: compression test in type 4 |
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| SGKent wrote: |
normal compression. Engine is cold. At 58,000 miles actual the original engine should still be almost virgin so one would wonder why the FI was abandoned for an inferior progressive carb.
Stock compression is 7.3 on buses. At sea level 14.7 (not hot, humid or low pressure overhead) X 7.3 is 107.31 PSI. The cam and cranking speed can affect it too. 107 - 98 is 9 PSI which is within 10% of what would be expected. I doubt if your gauge is a 1% precision instrument. If you are at a few thousand feet altitude, it is a hot humid day with a low pressure system overhead, I would expect the atmospheric PSI to be less. The readings you got would not concern me. |
THANK YOU!!!
Mind you what papers I have said "Engine Rebuilt, 14,000 miles" When in fact they didn't "rebuild" an engine....the put another one in. And not even the correct engine for that model year. Also replaced the tranny w/ a 5 rib, not the 6 rib 091 it's supposed to have. Hence my doubts about the health of the engine or the actual history.
Thanks. Being a pilot altimitry is part of my job. We're @ 1,000 MSL, it's hot and we've got high pressure today. Density Altitude is REAL and does affect NA engines quite a bit.
I rechecked it w/ the gas pedal to the floor. Went up to 100psi +5 -0 all cylinders. I left the gauge on for a while after the tests and in 10 min it only dropped @ 10 psi. I think it might be healthy after all. I'm still not trusting it until I can get some miles on it.
Crank Case pressure is very mild so I suspect the rings are good as there seems to be little blow by.
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78 Westfalia Campmobile Deluxe
As long as I have my Bus, I have a home. |
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Wildthings
Samba Member
Joined: March 13, 2005
Posts: 50348
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| Posted: Mon Jul 04, 2022 2:35 am Post subject: Re: compression test in type 4 |
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If the pressure is fairly even across the board then the engine is probably in good shape. Being even but a bit low would be an indication that whoever built the engine ended up creating a lower than stock compression ratio.
It is not that hard to fix a progressive so that it will work fairly well. |
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