The Stovebolt Site Forums The Shop Area Engine Shop 235 basic inspection

Okay, yesterday I pulled my 1958 235 out of the shop and spent the day cleaning the outside and the water jackets.

I wanted to just throw this engine in the intended truck and be done with it. It has okay compression, and I think it is driver quality. While I have it out of a vehicle, I thought I should pull the oil pan and clean out the sludge as I am going to use detergent oil. While cleaning, I found the remnant of one valve seal sitting loose so it looks like I need to investigate a little more...

I think you guys can see where this is going. I really don't want to go to the expense/time/effort of a rebuild, but don't want to stop short. What items should I check while the engine is out?

Paul

Sounds like you are getting closer and closer to this:

http://devestechnet.com/Home/Project1959235

It's funny how that sneaks up on a person. There are cheaper ways with a few tools. Checking the cylinders for uniformity and taper maybe you can get away with cylinder honing. Hard to not do that if you have to remove the head. That's just me though. Its why I have two 1950 trucks tore down to the last bolt. One thing leads to another. Be careful!

This is exactly the kind of thing that I'm hoping to avoid in my engine transplant and why I was asking the questions that I did (see my separate post on pre-install punch list). I know I need to either drill out the mounting holes or replace the plate, for example. Neither looks like a simple task, especially if I don't want to disassemble the engine. Like Paul, my engine runs and has good compression, although it smokes a little. I was hoping to get it into the truck and enjoy the truck while I worked on systems one at a time. Are we fooling ourselves in the thought of just throwing these into our trucks?

No, you aren't fooling yourself at all. These engines can go from the salvage yard after not being run for 30 years and you can run them fine for awhile.

The issue is, you will have this nagging feeling in the back of your mind that you have a total engine rebuild in your future at some point. As long as now isn't a better time than later to do it, you are fine. Nobody can answer that but you. I have a few trucks that I got running after sitting forever. It could be years before I need to address it.

IF you remove the head, while the head is off, see if there is a stamped number in the center of the top of the piston. If there is, thats the current bore size.

As far as drilling the front mounting holes, its outlined in the article on how to do it right, but if you can find a plate thats
already drilled and just transfer the hole pattern over, it will work okay. Everything depends on two things, your budget and your level of perfection. Good luck and have fun whatever you do!

The option of using an existing plate is one that I have available, as I have a plate. I've been wondering how I could use it as a template for drilling the plate that is attached to the engine. I'm thinking that I could clamp the extra plate to the one that needs drilling and go from there. However, I am guessing that I'll need to either lift the engine and go from below or lay it on its side and go that way. I think that there are pros and cons to either approach, I just haven't slogged through them all in my mind.

I agree with you about the nagging feeling about the salvage engine (which mine is). However, I just don't have the money right now to do a rebuild. It's either chunk it into the truck and see if it's driveable or wait a couple years saving up the cash. Seems like a no brainer for me. I want to drive the truck. So I'll live with that feeling. Assuming that I can get through all the rabbit holes and get to the point of actually doing the transplant.

Drilling from the bottom is a lot easier. Lay it on it's side. I used a triangle file to square the holes in the one I put in my Yard Dog.

Dumb question time: is it better to lay it on one side instead of the other? I'm guessing that I have to drain all fluids before I try to roll it over (not sure how I'm going to roll it over). Should I take off any accessories first? Oh the possibilities for messing up!

When I drilled my front mounting holes I drained as much as the motor as possible and set it standing vertical on the bellhousing on the floor. I still had quite the oil run down. I would recommend drilling the holes at 4 points on each hole as to help make a square form. I did use the template as help. I'm not sure if Cletis has brute strength, but my plate was very tough steel and filing was going to require a lot of work to uniform a square.

The only accurate way to measure using your other plate is from the face of the plate. Don't use the edge that sticks out with the holes. The center of the hole should be .955 (almost an inch) from the face of the plate thats bolted to the block. You want it just under an inch, not over because you need some meat on the edge. All the dimensions are in that article I posted earlier. If you use that edge I warn against, you may have that less than an inch on one hole, but not the other. GM wasn't very accurate on that particular edge. Not to worry though. It will come out fine!

To be clear, dont measure .955 out from the front face and mark there.. I am saying .955 from the face where the block meets. So subtract the thickness of the plate if you do that. Hope I am not confusing anyone.

Also, keep in mind that if you drill these holes from the bottom correctly, you will NOT be able to get the correct bolt in the hole from the top. If you think you can and use a big hammer, you run the risk of putting a hole in the cover. Read my explanation in the aforementioned article for a better solution.

The pics in your article are interesting. They clearly show the lack of uniformity in the plate. The difficulty that I will have is that I was not planning to remove the oil pan, so I wouldn't be able to determine the centerline from the crank. Not sure how I will handle making the measurements that you recommend since I am lacking a starting point.

And then the reality of the situation just sank in...the timing cover has to come off in order to get the carriage bolts into the new holes, unless you do the weldnut mod that you referenced in your article. Another rabbit hole.

Mike,

You can grind one side of the carriage head bolt and it will fit through with the oil pan attached.

Paul

Yep Paul you can do that. Or elongate the hole. Really, its just a matter of how much compromise you want to do. I have 5 engines sitting in my shop that have these holes drilled by the previous owner. All he did was measure 3 inches between the two holes, then 3/4" from the front of the plate. Its pretty close, but its up to you how far you want to go with 'close'. So what I did before finding out about how to do it right can be seen here:

http://devestechnet.com/Images/Projects/Project1959235/Project5923562lg.jpg

click on the picture and notice the two dimples made by a punch.
Had I not learned the correct way, that is where the holes would be centered. Point being, its not too far off, and maybe everything would be fine. If the plate is 1/8" thick, and I do not know off hand, then subtract that number from the .955 and you will be better off than the dimples I put in mine. Not sure its worth overthinking really. That is, unless there are other reasons to take the engine apart.

Paul, I am not sure how many percent you are degrading that bolt by halving the head. This is why maybe a weld nut on that side or both sides and bolt from underneath until you get it apart. Removing weld nuts are 101. Good luck guys! All part of the learning process. The nice thing about steel is, you can weld that hole shut later on, and do it right. No harm, no foul.

Guys,

Good info all the way around. I just can't bring myself to tear into a running engine without a good reason and to me, taking off the timing cover and oil pan are getting pretty close. I've actually wondered about the oil pan and whether or not I should drop it and clean it, since I know it was where the sludge collected and modern detergent oil will cause it to recirculate. I guess I can look for non-detergent oil, to keep the sludge where it is for now. What do you all think, worth the effort?

The simplest, most effective sludge treatment is two quarts of kerosene or Diesel fuel. Fill the crankcase with fresh 30 weight oil, then add 2 quarts of solvent. This raises the oil level enough that the crankshaft can whip the lube up into a very effective cleaning agent. Run the engine at a slightly fast idle speed (1200-1500 RPM) for 20-30 minutes. Then drain the oil while it's hot and refill with fresh oil. The dissolved sludge will drain away with the oil. Just DO NOT drive the vehicle or put any other type of load on the engine. The solvent compromises the film strength of the oil enough to damage a loaded bearing. Running "no load" is OK.
Jerry

I have decided to pull the head while the engine is in the shop. I figured I would need the head off to at bare minimum replace the valve seals. If the cylinder bores look bad, I will need to reassess. I guess I will be in the market for a complete engine gasket set at this point. I still haven't gotten much feedback on copper or composite head gaskets.

Sigh, I know where this is going, just don't want to dump tons of money in a yard dog truck.

If I read the post correctly(a big if). You decided to pull the pan to remove sludge. The center line measurement off the crankshaft will be simple. The timing cover will be simple to remove with the oil pan off. The drilling of the mount can be done after you get the measurements. I would roll the engine to the manifold side after I removed the carb and oil lines. Along with the canister if you have one. The manifold is stronger than the draft tube and the distributor. The valve stem seal can be addressed by pulling the rocker arm shaft. None of this is hard to do. Don't worry yourself into a lot of money yet. These old engines aree happy campers most of the time. Get it started, does it have oil pressure? yes, good. No? shut it down and find out why. Is the compression good in all cylinders? Cool. If not, then worry. It might just take some time to reseat the rings. It might take a few miles to loosen the rings and piston. It might be worn out but that will show with not too much spent yet. With the timing cover off I think the bolts can be placed for the mount.

Paul, with the head off, see if there is a number in the center of the piston top. That would be the current bore size. If nothing, that may be really good news since it might mean it hasn't been bored at all yet. Or they didn't stamp the pistons. But if its there, you will know something you didn't.

Also Paul, if its a yard dog truck, use whatever head gasket comes in the kit. But if you have plans for it, go with Copper. IMHO

Even though its considered a WAAAAY over the top article by many here, peruse it anyway because there is always something that may help you decide what avenue to take in other peoples opinions. http://devestechnet.com/Home/Project1959235

The one thing that I thought was a good statement as far as philosophy is.. This venerable engine deserves the treatment you would use when installing it in a treasured vehicle. Not a trailer queen, or show truck, or anything like it, rather a TREASURED vehicle. Lots of amazing talent here. Ask questions no matter how stupid they sound because we have ALL been there.

I had some time to mess around with this old 1958 235 engine, and below is what was found:

Here it is after cleaning
[img]http://www.surfacezero.com/g503/data/3285/medium/IMG_6657.JPG[/img]

1) The valve train oiler (don't know the real name for this part) was cracked in half. I looked around on the other various vintage 235 engines I have and this one is different than all of the others...it looks similar to those on babbit engines, and the one on a 62 235 appears to be pinched closed. What am I supposed to have on a 58, and where to find?
[img]http://www.surfacezero.com/g503/data/3285/medium/IMG_6661.JPG[/img]

2)All of the cylinders looked real clean with no scoring, and only a slight ridge. I don't have an inside micrometer so I cant get any accurate measurements. Looks like stock pistons as I didn't see any oversize markings. I may re-ring or just install a new head gasket and call it a day?
[img]http://www.surfacezero.com/g503/data/3285/medium/IMG_6680.JPG[/img]

3) This item I didn't really want to see...looks like there was once an issue with the number 4 exhaust valve although the valve looks fine now. There is no evidence of cracking or burn through. Do you all think this is okay?
[img]http://www.surfacezero.com/g503/data/3285/medium/IMG_6683.JPG[/img]


Guidance/input is requested.

Having fun,

Paul

Looks good Paul. What does the shop manual for 1958 show as far as that oil tube contraption? The 59 doesn't loop back to the reservoir. ALL of the upper end goes thru the main tubes. Hopefully someone will say something on this?

No number on the pistons so maybe its the first rebuild. Nice!

I have a 46 2-ton that I use for my business. I have had it for about 4 years and 2 1/2 of those years it has been in service and makes deliveries weekly. My employee's use it as well... Last winter I thought I would pull the engine to freshen it up. We were a little slow and I had about a 4 week window that i could afford to have it apart. It ran well, smoked a little and used some oil! But it ran well.

When I pulled the head I found aluminum pistons. I thought that was a good sign! Remember, it ran well. I thought I would freshen it up with new rings and reseal it... Well. It had .060 over 216 pistons in a 235 that had a .020 over bore at the bottom of the hole and... Wait for it... .040 over bore at the top of the hole. To simplify that.. Standard bore pistons in a .040 cone shaped hole...

I had purchased a crank and rods on eBay to swap over to full pressure oiling, but I found that the babbit bearings were perfect. I ended up having the pistons that came with the rods fitting to the bores, ground the seats and reassembled everything.

My point is, I had less than 4 weeks of the truck being apart and my engine is now rebuilt and looks great. That was last winters project. This winter I pulled the cab off and restored it as well as building a new bed!

I would buy or borrow an inside mic to measure for cylinder bore taper (top compared to bottom), then if it is acceptable, put in a new set of standard rings.
I wouldn't worry about the accidental intake valve recess in the piston/block. I think that the area of the dent in the block will have enough head gasket surface area to prevent blowing out the gasket. If it should fail (unlikely), you will know before catastrophic failure occurs. Your only other preemptive choice would be to find another block.
Carl

I wouldn't worry about the dent. I don't remember, but I would imagine that is not a sealing surface if the valve hit it at some point? The head gasket sets further out and I wouldn't worry about it at all...

That tube is the pressurized oil from the left side of the block that runs through the cooling jacket to the right side and then up through the block and head and feeds oil to the rocker arm shaft. Mine was not cracked, but it was completely clogged. I didn't take a chance and ordered a new one. It was of course back ordered and I wanted my engine back together so I ordered all the stuff from McMaster and made my own. Then the back order was filled. Sooo.... If you need one, I have a brand new one that you can have for what I paid for it. I'll even through in the shipping for free!

Good to hear that you all don't think the valve strike is fatal. What caused the engine to drop a valve like that?

The oiler part is called a "connector assembly" in my 1942 parts manual. There seems to be many versions of these during the production of the 235. Was GM chasing oiling problems and coming up with new fixes? Randy does the connector assembly you have look like the one in my image?

I will see if I can find a used piston ring to measure the difference in cylinder taper, found this nugget from Jerry years ago.

https://www.stovebolt.com/ubbthreads/ubbthreads.php?ubb=showflat&Number=683766

Thanks for the help.

Paul

"1) The valve train oiler (don't know the real name for this part) was cracked in half. I looked around on the other various vintage 235 engines I have and this one is different than all of the others...it looks similar to those on babbit engines, and the one on a 62 235 appears to be pinched closed. What am I supposed to have on a 58, and where to find?"

image of part in question?

All 216/235/261 engines had a line or a journal to feed oil to the rocker arm assembly.

rocker arm lubrication
internal lubrication to the rocker arm assembly

People sometimes pinched the tube on the rocker-arm assembly - as an attempt to increase oil pressure in the engine (I think).

The new connector assemblies are straight pipe with the fitting brazed on. You have to bend it to shape. I ended up with a pipe thread to compression fitting from McMaster. I then drilled out the center of the fitting to allow the tube to pass all the way through the fitting. Fairly simple...

Your main thing is that you have to seal the coolant from the oil line and then seal that from the outside. The return is restricted so that all the oil doesn't just flow out of the tube and not oil the rocker shaft. I think some years has a restrictor in the end of the tube and some years they just pinched off most of the tube.

My 46 has the restrictor, but I have seen plenty of them pinched off from the factory.

Measure those bores and find out if your rebuilding or freshening up!

Yeah, Randy is talking about an older style. In the newer style there are actual passages in the engine and no copper tube until you get to the rocker arm assembly. Look in the 1958 Shop Manual and there is a picture of the proper part that you need in its original configuration.

The motor machine shop will take care of deciding what to do about the cylinder taper.

All the plumbing possibilities are shown at links in my post above.

All of the different styles of connectors are also shown (with part numbers for the last generation).

Tim,

Your documentation links are always useful, thanks. It looks like there are at least 3 different connector assemblies in the lifespan of the 235. I have noticed that some of them have been "mechanic modified" by pinching the tube in order to lessen flow.

Now to find one that is not gold plated. Anyone have a decent used connector assembly part number 3836566?

Paul

I didn't know this until this rebuild, but in 1959, they chose to pinch off the end by just not even having an end to pinch off. All of the oil goes through the rocker shafts. I think there were changes made besides just that in the rocker shaft. I dont have an extra one like you need Paul, or I would send it to you.

To be honest, I don't see how any oil flows into the rocker shafts with the connector assembly used on 1955-58 engines. Without any constriction in the pipe, it would seem that all the oil would flow through the metal pipe and little to none in the rocker shafts. What would happen if the later generation connector assembly (1959-62) was used on a 1958 engine?

Information regarding the oil pathways on different "generation" engines is shown near the bottom of this page , and more detailed information for different years is shown on other pages).

I think you do not need the special "hollow" bolt from 58-62. My guess is that you could use the 59-62 connector with the 1958 block/head/rocker-assembly.

Pre '68 Dave might chime in with clarification/correction.

DO chime in Dave. The reason I am curious is because for them to remove the reservoir tube completely and just rely on the rocker shafts, wouldnt there have to be a larger orifice or a different configuration concerning the rocker assembly?

I will start with this write-up of mine.

1958 and earlier should not have a crimped tube but there is more to it than just that.
Up through 1958 the engines had a 1/16" orifice restricting the flow of oil to the rockers. Starting in 1959 the orifice size was increased to 11/32". This larger orifice offered almost no restriction. At the same time the overflow tube on the rocker connector was pinched off. Also at the same time the groove inside each rocker was offset 1/4" so it did not line up with the supply hole at each rocker. This prevented oil from squirting out of the vent hole on each rocker.
If you use 1958 or earlier rockers on a 1959-62 engine you will have the best luck if you restrict the oil supply. Chev did this on replacement short blocks by selling you a plug to put in the block to block the original oil path and a special drilled head bolt drilled with a 1/16" hole for the oil to pass through.

Feel free to ask further questions.

Dave,

Thanks for the description. The difference in orifice diameter would certainly explain the oil flow pressure. Where exactly is this either 1/16th or 11/32th orifice?

This may explain why some lubrication issues arise when parts are mixed and matched. I have a "Frankenstein" parts engine that is an agglomeration of many year components. It has a 59 block, 54 head, and the connector assembly looks like the 1955-58 part but it had been pinched off (obvious backyard operation) similar to as on a 1959-62. What seems to be compatible may not be...

Paul

Up to 1957 the orifice was in the fitting that screwed into the block at the rear, under the side cover, that the rocker supply tube attached to.
Starting in 1958 Chev propped the supply tube under the side cover and changed to a cast in supply galley. On the 1958-63 engine, if you look under the side cover, in the center top, you will see a 1/8" pipe plug. The orifice is behind that plug.


Paul, I would suggest pulling a rocker from the shaft and see where the groove inside it is located.

Thanks for the descriptions and references, the changes of the oiling system in the lifespan of the 216/235/261's are a little bit clearer to me know.

Always fun to learn something new, even if it is learning technology from the 1930's era.

Paul

This is still a work in process, but I started a post on my Blog today covering rocker oiling. LINK

Nice, Dave

Thanks

Thanks Dave, nice description.

Are the rocker shaft oil hole locations the same on all 1954-62 engines?

1940-62 all have the holes in the same places.