Valve galley issue

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Model T Ford Forum: Forum 2018: Valve galley issue
Top of pagePrevious messageNext messageBottom of page Link to this message  By Val Soupios on Saturday, January 06, 2018 - 08:51 pm:

I have an ‘14 engine that I started up for the first time and it is smoking quite a bit. The engine has not been rebuilt to my knowledge but other than the smoking issue, runs well with good even compression. Oil was dripping from the valve covers so I decided to replace the gaskets but when I loosened them oil poured out. After I cleaned things up I found that there are no return holes to allow oil to return to the sump. I checked another ‘14 block that I am working on and it has 2 drain holes. Has anyone else encountered this problem and if so how did they deal with it. I am concerned about drilling holes and getting chips into the sump but don’t want to pull the engine and tear it down to do it. I am also not sure how the oil gets up there in the first place unless it comes up through the lifters and is supposed to drain back through the holes that are not there.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Spencer Vibert - Granby ,CT on Saturday, January 06, 2018 - 08:58 pm:

Val I rebuilt a late 13 early 14 and it did not have drain back holes that is why the one I had smoked drill 2 5/16 holes and you will be fine


Top of pagePrevious messageNext messageBottom of page Link to this message  By Philip Berg on Saturday, January 06, 2018 - 09:13 pm:

My 11 didn't have the holes either, drilled with a 3/16 drill if I remember right, problem solved.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jack Putnam, Bluffton, Ohio on Saturday, January 06, 2018 - 09:17 pm:

You can catch the chips by placing a small magnet next to the drill bit when drilling the return holes.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Duey_C-west central, MN on Saturday, January 06, 2018 - 09:28 pm:

I've used a vacuum cleaner to suck up chips while drilling to keep them from going inside something.
I like the magnet idea too. :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Val Soupios on Saturday, January 06, 2018 - 09:28 pm:

Thanks, that is what I will do. Hard to believe so many blocks got through without the holes being drilled.


Top of pagePrevious messageNext messageBottom of page Link to this message  By George Barclay in west Michigan on Sunday, January 07, 2018 - 08:07 am:

I put grease on the drill bit it will help hold t chips from falling the hole.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Andy Loso St Joseph, MN on Sunday, January 07, 2018 - 08:11 am:

I usually use sour cream and onion dip for my chips, but a good salsa works well also.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Val Soupios on Sunday, January 07, 2018 - 09:10 am:

Andy I am down by the beach so I usually opt for clam dip!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Adam Doleshal on Sunday, January 07, 2018 - 10:24 am:

You have to remove the pan inspection cover & shoes prior to drilling, then carefully remove any chips that fall in the crankcase! Try as you might, there is no fail-proof way to avoid some chips from falling in.

The “drain holes” in the valve gallery were added around October 1914. Prior to that, each tappet bore was broached with shallow oil grooves which allowed oil to fill the valve galleries with oil to the level of where the tappets come thru the block and also allowed accumulated oil to drain back to the crankcase.

The problem of “oil burning” due to completely filled valve galleries on these “pre-‘15” engines mostly occur in two ways:
1) When your engine is so dirty inside with carbon & sludge that the grooves are plugged.
2) When an inexperienced Model T engine builder reams the tappet bores out oversize and effectively removes the oil groves and does not know to re-broach them or drill later style holes.

Either of these circumstances will cause the valve galleries to slowly fill with oil until the level reaches the bottom of the valve guides. Once the bottom of the intake valve guides are even with the oil level, an excessive amount of oil is drawn up the valve guide and into the cylinder on every intake stroke.

The later style holes are 1/4”. The size is engineered so the valve galleries do not over-lubricate or under-lubricate.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Val Soupios on Sunday, January 07, 2018 - 01:01 pm:

Thanks Adam. That answers almost all my questions. I guess I will drill two 1/4” holes. One remaining question is how does the oil get up there in the first place if the oil grooves were reamed away or are clogged. I would think that if the oil can get up there in the first place it should also be able to return the same way but that clearly isn’t happening. I suppose it is possible that gravity is not enough to do the job of returning the oil while the splash system has enough force to get the oil up there. Anyway, once I drill the new holes I will know for certain if that is the cause of the smoke.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Adam Doleshal on Monday, January 08, 2018 - 11:27 am:

Great question! With clogged or non-existing oil groves in these pre-‘15 engines, the oil will fill up the valve galleries due to vacuum. The exhaust ports and area around the exhaust valves have very little to no pressure because the stock exhaust system flows quite well at all speeds. The intake manifold, intake ports, and thus any clearance around the intake valve stems are constantly under vacuum when running. The vacuum present at the intake valve stems is enough to create vacuum in the valve galleries and draw oil around the tappets faster than the oil can drain back. As soon as the oil level in the gallery reaches the bottom of the intake valve guide/guides the car begins to smoke.

I’ve diagnosed and repaired this issue on a couple cars.

The standard scenario is that the car starts & runs normally. Then upon driving some distance it begins to smoke (obvious oil-burning). If the car is shut off for some length of time, it then will not smoke until it is driven some distance again. Even with small clearance at the tappet guides, the oil generally will drain back into the crankcase in a few hours time and much faster if the engine is hot.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Val Soupios on Monday, January 08, 2018 - 12:51 pm:

Thanks again Adam. I think I now know what has to be done and why. It is great to have this Forum as a resource.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Spencer Vibert - Granby ,CT on Monday, January 08, 2018 - 01:16 pm:

Sorry you need 2 3/16 holes not 5/16


Top of pagePrevious messageNext messageBottom of page Link to this message  By Adam Doleshal on Tuesday, January 09, 2018 - 11:12 am:

Probably close enough, but the holes are 1/4” “by the book”...


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