The Stovebolt Site Forums The Shop Area Engine Shop Engine autopsy help needed

Hey Everybody,

This post is a companion post to my latest project journal entry. You can read up on what got me to this point there. Bottomline up front: I've just taken the cylinder head off of my 1961 Chevy 235 engine. It was a car engine, so it has hydraulic lifters and no modifications. It was spewing smoke the last time I tried to drive my truck (1953 Chevy 3100) and here I am with the head off. Here is the text from the project journal entry:

"Hey Everybody,

It's apart! Multiple pics attached. Biggest bit of info that I could see is everything on the passenger side is wet with coolant. Also, dead center of the driver side is an obvious coolant blowout. There, it actually ran down the outside of the block. Based on the wetness and condition of the valves, I'm wondering if #5 and #6 were really firing or not. I forgot to snap some pics of the valves, and will do thst later.

I wasn't able to get the lifters out of their holes. It's like suction held them in place.

Pretty decent ridge ring at the top of each cylinder. I couldn't find any markings on a piston to indicate an oversized one. I think this might be an honest, original and very tired engine.

Ok, folks. NOW is the time to speak up! Thoughts? Next steps?!?"

I have lots of questions and am hoping for some input from everyone out there. Please!

It looks like you have a "rebuildable core" engine there- - - - -strip it down to a bare block, get the cylinders bored just enough to straighten out the taper wear, regrind the crankshaft if necessary, and install a new camshaft and solid lifters. (Melling CCS-1). The only hydraulic lifters that are available these days are made overseas, and the failure rate right out of the box is ridiculous. It's possible to use different (less expensive) lifters for AMC/MOPAR engines by sleeving down the stovebolt lifter bores a few thousandths. Drop me a PM if you like- - - - -I'm working on developing some major modifications that use newer, less expensive and more available rebuilding parts for non-stovebolt engines.
Jerry

I agree looks like a rebuildable engine ,You found were the head gasket was leaking ,looks like was leaking into the two cylinders a bit also .Most likely the oil may have been a head problem also .If you decide to take it apart for rebuild take lots of pictures and mark were everything came from.

Well, TBH, I was hoping that someone would say to replace the head gasket, clean things up a bit and send it. Maybe get a couple of years of additional service as I save up for a full rebuild. But, if it needs to go to the machinist, then it needs to go to the machinist. This is new territory for me, and I don't even know what I don't know. When trying to determine if a shop is worth the risk, what questions do I need to ask and what answers are appropriate? What are red flags that should send me away? Given that I live in the mid Atlantic (a high cost area), what kind of pricing is reasonable? Am, I better off in the long run giving up on the antique (read expensive) engine and making the necessary modifications to adapt a newer, more supported engine (read as less expensive in the long run after the initial investment). I'm not looking for more horsepower or tire shredding torque, just something that I can reliably putt around town in. Even down VA State Route 3 (IYKYK).... Thanks in advance.

Can you post pictures (or did I miss them) of the combustion chamber side of the cylinder head?

Good engine machine shops are getting hard to find so the best recommendation is to talk to others in your area that may have had work done to get a better idea of who to trust. I don't know if you have race car engine builders in your area but they have a lot more experience than general vehicle user types.

Replacing the head gasket isn't likely to provide any benefit to your original oil smoke problem, however if it was coolant smoke (white) then replacing the gasket could help. It's not ideal by any stretch but the cost of cleaning things up and replacing the head gasket is mostly your time. You indicated #5 and #6 may not have been firing but the head gasket failure is not adjacent to those cylinders so understanding why they would not have been firing is an important piece of information.

WIC,

Attached are combustion chamber pics of all cylinders. The space between #4, #5 and #6 are all wet. This is why I was thinking it was coolant. While the engine likely was burning oil, I've maintained from the beginning that it was also burning coolant as the "smoke" often dissipated as steam does. I guess I'll never know for sure....

Mike - Just an observation from my zoomed in look at your latest head pictures. I snapped a pic and have marked what looks like a crack in the casting between cylinders 4 and 5 (see below). That would make me want to at a minimum take the head to a shop and have them clean it and check for warps and cracks before doing any other work on it.

A cracked head IMHO means it's time to go find another head unfortunately.

It could be with another head you could maybe get a little more life out of the engine, but if your going to go as far as replacing the head, that's not very far from just taking the whole engine in for a check before sinking money into it. A little money spent to rule it re-buildable or not is well worth saving yourself from agony of finding out after much work has been done that it really wasn't good to start with.

I would suggest the same as WICruiser on seeking out folks in your neck of the woods that have a known reputation with other folks of doing good work. The best folks to work on stuff I've ever found have always been found starting with word of mouth information from local folks.

GDads,

Eagle eyes! It sure does look like a crack.... Attached are 2 pics, a close up of the suspected Crack and the corresponding area on the gasket. This area is between ##2 and #3. It's dry towards the top of the pic (driver side) and is wet at the bottom. I do have a spare (derelict) engine on hand. It's the one that came in the truck and had the rusted out lifter (detailed in my project journal).

I'm reposting this pic to go along with the previous 2 pics. It aligns nicely with the Crack between #2 and #3 and the passenger side being wet while the driver side is dry. Makes me think that coolant was escaping from the crack, moving downhill towards the rear of the engine and found a way into # 5 and then #6.

Being that your in Virginia, I would reach out to the ODSS group for recommendations on Machine Shops.

I had a good machinist in Suffolk Virginia who knew these old engines inside and out, unfortunately the old man passed away recently.
You need an old guy, or a younger guy who learned from the old guy. Getting harder to find every year.

Try to find a machine shop that's willing to do a good cleanup, magnaflux, and possibly a pressure test to see if the head is a good candidate for rebuilding. If there's no serious damage, do a valve job and mill the head just enough to smooth it out. Don't let anyone persuade you to install "hard valve seats for unleaded gasoline"- - - - - -it's mostly a scare tactic to increase the shop's bottom line. Stainless steel exhaust valves for a small block Chevy V8 are a drop-in fit, and they accomplish the same thing as stellite valve seats at a fraction of the cost.

That's what I did with my 261.

There's absolutely no reason to spend money on hardened valve seats. The standard story is that you'll burn an exhaust valve because there's no lead in the gas.

Well there has been unleaded gas sold in the United States for over 100 years. Amoco first came out with unleaded super premium high octane unleaded in 1923.

And nobody ever heard of exhaust valves on any cars getting burned as a result of burning amico super unleaded in all of that time.

All I ever drive are antique cars. And all of them have been getting unleaded gasoline because I was never around when leaded gas was still for sale.

Unless you're Auto crossing your vehicle and revving it at the red line all the time you're not going to burn an exhaust valve running regular unleaded in your truck.

The picture the head shows cylinders #5 and #6 look wet, but cann't tell if it's oil or coolant. If the head gasket wasn't compromised around those cylinders I suspect oil and reinforces the oil smoke you experienced. From your other post regarding the crack in the block it could be a mute point but I suspect that there are serious problems with the rings in cylinders #5 and #6 although it could eb intake valve guides. You could pull the intake valves from those cylinders and see what the valve to guide clearance and seal conditions are to help answer the question.

It sounds like you may be between a rock and a hard place if your current block is cracked and your original engine has significant issues preventing it from being a rebuild cantidate.

Hey Everybody,

Can someone provide exact part numbers for the correct stainless steel valves? I feel like I'll have a better chance of success speaking with someone if I have that info already.

Thanks!!!

Mike - Here's the valve part numbers for your '61 235:

GM Parts Group 0.296 - Valve, intake, GM# 3815082

GM Parts Group 0.297 - Valve, exhaust, GM# 3731212 / replaced by GM# 3839387 07/66 (this is also the standard Chevy small block exhaust valve for that time period)

If you're on the hunt for some, the following are currently on evilbay:

6 each NOS GM# 3815082 intake valves Note: These have some minor surface corrosion/rust which should be able to get cleaned up to put these to work and it's a decent asking price IMHO.

12 each NOS GM# 3731212 exhaust valves Note: These look really good and enough for 2 engines, making the asking price really decent IMHO.

If you'd rather have brand spanking new replacements:

The Filling Station AF-18 List price $12.95 + shipping each.

The Filling Station AF-16 List price $7.75 each + shipping

Happy Hunting!

Edit Note: These are not "stainless steel" valves, just the stock or stock style replacements. If anybody has part numbers for correct stainless steel valves, it would likely be Jerry "Hotrod Lincoln". I'm sure he'll chime in when he sees this.

Just buy these and have your machinist use them when he does the valve job. You'll end up with two extra valves, so just give them to the machine shop. You'll end up WAY money ahead over hard seat installation.

www.ebay.com/itm/274430393424?

Jerry

If you buy new valves, check the width of the seats. If they are too wide, it will burn any valve. I still use three different stones, but I understand there are cutters that do it all in one. I would still lap them after however you cut them. But don't just lap them because that will make the seats even wider.

Hey Guys,

Stupid question time. Is there a downside to taking the cylinder head from the 2nd 235 that I have (non-running) and putting it on the engine block that is currently in the truck? Both heads are the "848" variant. I was thinking that I'd keep the lifters, push rods and rocker arm assembly that's in the truck and only swap out the head/valve/springs assembly.

Several days ago, I put oil into #5 and #6, to see if it would drain down past the rings. It's been almost a week and it's just sitting there. This makes me wonder if the oil was running past worn valve seals instead of coming up past worn rings.

Can I make that logic jump? Other than time and the cost of gaskets, am I risking doing damage to either the block or cylinder head?

Thoughts? Be gentle....

I don't think that's a stupid idea at all. You have nothing to lose. You really can't make anything worse. Just make sure you adjust the valves properly before starting the engine so you don't bend a pushrod.

Clean up the head you are going to use and maybe lap the valves with some laping compound that way you know the valves are free and you will be able to see if they are sealing. Laping compound and the suction cup tool are cheep and do a good job.

Your test of putting oil in the two suspect cylinders isn't really really going to tell you much, as there's only gravity forcing oil past the rings, but while running, there's both compression pressure and the movement of the rings in their grooves that will help oil get past. The oil control rings are supposed to remove most of the oil splashed against cylinder walls back down to the crankcase, and if they aren't doing their job, that oil can get past the compression rings into the combustion chamber.

Typically oil leaking past valve seals, especially on intake valves will cause smoke on first startup and on deceleration when vacuum pulls the oil past the oil seals. I don't recall if you posted about smoke out the tailpipe.

But cleaning up one of your heads and maybe renewing the valve seals on it, along with lapping the valves like Kevinski suggested to check the seats, would probably take the possibility of the issue being valve seals out of the picture.

If you're torn down far enough, honing the suspect cylinders and replacing the rings in those two might be another step in the right direction. But oil is still relatively cheap compared to a complete overhaul.

Definitely worth considering the head swap.

I agree with Kevin about your ring test but given that you are not in a position to honing the suspect cylinders (if I understand correctly) without significantly more effort the head swap would help idenfiy if the problem was with the head or the block. I beleive you had a coolant leak from a crack (?) in the block which may or may not be part of your problems but it could be that the head gasket replacement will seal that up at least for the short term.

As others have said removing the valves to inspect the guides and installing new stem seals would help confirm if the previous head or the block was the primary issue.

Hey guys,

What tool(s) will I need to get the valves out for inspection and then reinstallation? Are these tools that I can rent locally?

Thanks!

You will need a valve spring compressor, I beleive the large "C" type that pushes on the head of the valve on one side and the spring retainer on the opposite side should work but I do not have personnal experience on this head type to know for sure. I looked at Oreillys tool loaner program and they have a tool (67057) that may work - it basically connects to the spring near the head and presses down on the spring retainer. I have used a similar one to the Oreilly one to remove a valve spring on head installed on the engine such that I could not use my "C" clamp type.

All of the major chain stores will loan them to you for free. There are several different designs.

When I had to replace a broken exhaust valve spring on a '66 Toronado, I picked up 3 different tools from Auto Zone, Advance, and O'Reilly. As it turned out, one style was easier for removal and another design was easier for installation.

Get whatever ones are available and figure out which works best when you get them in the garage. Since they're free, it doesn't matter if you borrow one and don't use it.

If you wind up buying a valve spring compressor tool, be sure you're able to return it. I got one from Amazon and it didn't work at all. It was just not set up for the head. It was a C-type with toggle leverage, but it couldn't span far enough to be able to even start moving the lever. It got returned in short order.
The rental approach is the way to go. Get the biggest and baddest one that they have. You'll have to put a deposit down, but that's 100% refundable when you return it within the prescribed time. O'Reilly is 48 hours IIRC.