B Compression test
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Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=176200
Printed Date: 01 May 2024 at 6:08pm
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Topic: B Compression test
Posted By: jlbintn
Subject: B Compression test
Date Posted: 23 Nov 2020 at 3:33pm
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number 1 - 105 psi number 2 - 100 psi number 3 - 85 psi number 4 - 105 psi Tested it after warming up to operating temperature, all plugs out, throttle wide open. This was my first compression test, and followed the instructions that came with the kit. Edit to add: Service manual = 115 psi
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Replies:
Posted By: DrAllis
Date Posted: 23 Nov 2020 at 3:38pm
| Might check for a tight tappet on #3. If it starts good and runs fine for how you use it, leave it alone. You grind valves and it may start to use oil afterwards and then you'll want to install new pistons and sleeves. |
Posted By: jlbintn
Date Posted: 23 Nov 2020 at 3:41pm
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Thanks. Just had the head in the shop, checked out good, no cracks. Cleaned, milled and pressure checked, and a new valve installation. |
Posted By: HoughMade
Date Posted: 23 Nov 2020 at 3:43pm
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If it runs fine, I would think nothing more about it until it starts not running well.
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Posted By: Dick L
Date Posted: 24 Nov 2020 at 6:09am
| I would dump in a can of Seafoam and recheck it after 10 - 20 hours of run time. |
Posted By: jlbintn
Date Posted: 24 Nov 2020 at 8:47am
I like the way you think. Already had that in the works. Sometime in the next day or two, I want to run it up to operating temperature, pull the valve cover and re-check the valves. I set them, after putting the head back on the tractor, but I'm thinking it might be worth a second check. Won't hurt anything. I know it's leaking oil, predominantly in the area of the rear main seal. It's not pouring out, just a trickle leak. I do not know if it is using oil, it will take more use to determine that. It is running good, and I suspect I can live with it. I actually have no problem with proactively re-building the motor, but I have two problems: I do not have the expertise to do it myself, so I have to find somebody that can do it. That is the easier proposition. The second problem is getting it off of the tractor and getting it to somebody that can do it. If I do not have to go there, I will not. I can live with it, as long as it lives with what I need it for
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Dick L wrote:Posted By: Dick L
Date Posted: 24 Nov 2020 at 4:08pm
| To replace the rear seal you would need to split the engine away and remove the flywheel. Not a big job if you have the experience. Not having that it is add oil when needed. BTDT. Before I became crippled up I built a fixture for a mill turn table and machined the seal housing and installed a lip seal For a D 10 thru D 15. If you can find a D ?? housing it bolts in place the same as your. Something to keep in mind if you rebuild your engine. I found all this out when I used the D ?? crankshaft, camshaft, oil pump and the seal housing in building a pulling engine for my C. Expensive machine shop machining, grinding and boring as the crankshaft is not interchangeable as is. However both crankshafts start with the same casting centers front to back. |
Posted By: jlbintn
Date Posted: 26 Nov 2020 at 12:30am
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I would rather not rebuild the engine, unless it forces me to have to do it. I have been using Rotella 15W40 in the motor since summer. The leak appears at the bottom of the bell housing underneath the tractor, and out of the timing opening. I think I can live with it. I am assuming it may use oil after all these years, but heavier oil may help, and I am hoping the soot control properties of Diesel oil will help clean up the engine. It's kind of a crap shoot. The tractor is running well. Oil pressure is only dropping below 18 at low throttle during idle. That is an improvement since the head was re-worked and installed. Any thoughts on using a quart of Lucas next oil change? |
Posted By: DrAllis
Date Posted: 26 Nov 2020 at 6:48am
| On splash lubed rod bearings??? you are heavy enough already in my opinion. |
Posted By: Dick L
Date Posted: 26 Nov 2020 at 7:48am
| I agree with Dr Allis that heaver oil would not be the best way to go. In your engine the condition of the bearings has nothing to do with oil pressure. The pressure is built between the check ball in the stem of the oil pump and the media in the oil filter. Either place that would fail would result in a loss of oil pressure. Rod, main or camshaft bearings can be totally gone and still have full oil pressure with this system. Your rear main seal would be either cork or felt. Both can dry out from setting as well wearing out from run time and leak. The same with the front. |
Posted By: jlbintn
Date Posted: 26 Nov 2020 at 8:35am
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So, just go straight 30 for the oil? I know oil quality and longevity has changed a lot since these tractors were manufactured. |
Posted By: DrAllis
Date Posted: 26 Nov 2020 at 8:38am
| 15W-40 is actually a little lighter in viscosity than old SAE 30 weight. By the numbers it shouldn't be, but it is. Stay with what seems to be working for you. |
Posted By: jlbintn
Date Posted: 26 Nov 2020 at 9:12am
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Thanks again, DrAllis. The oil that came out of the tractor on the first change I did was pretty black. It was also low. I have no idea how long this tractor sat unused between the time I got it and it's last use. I know that the gearbox had moisture in the oil. After one change, then a drain and flush with kerosene, followed by a day or two of drip draining fixed that issue up. The old dust boot on the shifter was cracked, it was one of the first things I replaced. I am assuming that is how water got in there. For the most part, I have spent the last 11 months establishing a new baseline. Dick, the front seal does not leak.
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Posted By: jlbintn
Date Posted: 27 Nov 2020 at 5:37pm
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The exhaust valves in 2 and 3 were a bit tight. Adjusted them, and re-did the compression test Results were the same for 1,2 and 4. 3 read 100.
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