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Well, after several weeks of smooth running & commuting, my DeSoto S13 Custom finally refused to start one cold morning, a few weeks ago. Tonight I finally got it towed to a mechanic who is old enough to appreciate & understand these old cars.

The first thing he pointed out was that the thermostatic coil spring was not functioning, & that I'll need a new housing. I guess I'll look around for this exhaust manifold mounted spring.

Meanwhile, we'll see what he discovers is wrong with her tomorrow.

ss

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The first thing he pointed out was that the thermostatic coil spring was not functioning, & that I'll need a new housing. I guess I'll look around for this exhaust manifold mounted spring.

Are we talking heat riser here? If so, they all go bad. Most folk force them to the open position, or remove them. They are not easy items to locate.

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Alas, the problem is much worse. I was told that it may be that the timing chain is skipping, since the compression was almost non-existant in some cylinders. I'll need to find someone who can replace the gear & chain.

The car was running slightly rough prior to it not being able to start, so the chain diagnosis may be correct.

ss

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  • 1 month later...

From my observations, a timing chaing doesn't "skip" and then "un-skip" . . . it jumps one tooth and stays there. It does thing due to wear on the sprockets and wear on the chain, combined. This generally has no affect upon compression as the both valves still close at the same time as always, just at a different reference point compared to the crankshaft, usually retarded.

Running rough or "no start", with backfiring through the carb during dranking, are signs something's wrong in this area. IF you can advance the distributor about one plug wire's "notch", and if things seem to get better, that's a sign the cam timing is off. That's how I saw a service manager a the local Chrysler store determine a timing chain had jumped on a police car years ago. It was running flaky and advancing the distributor's timing one plug wire's worth made the engine idle as it should. This "no start" issue is not related to ambient temp at all, but constant with every start.

I don't recall the specific engine in your vehicle, but I suspect it's a flathead inline motor. In this case, it could well be "gears" which run the camshaft rather than the sprocket/chain combination in V-8s

It is quite common for the heat riser to be stuck in many older engines. Main thing is that it's stuck open, or partially so, rather than closed. You might be surprised at how common this situation is (or was). ONLY area it might affect is cold weather warm-up performance, if it's closed, things will be come a little more "cold-natured" after the first fire-off, until engine heat transfers to the intake manifold.

Just some thoughts,

NTX5467

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How many miles are on it? Typical engine life between overhauls for a flathead DeSoto is 80,000 more or less. If neglected, as little as 50,000. In exceptional cases, 100,000 or more but 80,000 is par.

If it was in my garage the first thing I would do is look at the oil pressure, and test the compression. If oil pressure and compression are up to spec then I would do a tuneup and replace the bad choke. If compression and oil pressure are bad it is time for a motor job. This is not the end of the world as this is a very simple motor and all parts are available reasonable.

Low compression, hard starting and backfiring are consistent with burnt valves and a generally worn out motor.

The valve train is low stress and timing chains seldom give trouble, unlike newer OHV engines.

You need a competent mechanic. See if you can find an old gray haired or bald headed guy who is used to working on the old models.

Incidentally the part you need is called a Sisson choke. NOS ones turn up on Ebay from time to time. Antique parts speciallists sometimes have them but they are pricy.

Edited by Rusty_OToole (see edit history)
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Thank you RustyOToole & NTX5467. Although there's no way of knowing for sure, I think there are well over 100,000 miles on it. The engine is a flathead 6-cyl (in-line?). & there IS a timing chain, according to the shop manual. The compression was almost non-existent in some of the cylinders. Glad to hear it's a simple engine, & all parts are available at reasonable prices. Maybe it's not the timing chain after all. I'll pass on these remarks to the old, grey-haired (or bald) guy I find.

Thanks again.

Stan

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Low compression on "some" cylinders is not a sure sign of a timing chain having jumped a tooth or two. It is a good indication of worn rings and/or tapered or ovaled cylinder walls. Of course it might be nothing more than needing a valve job. A leak down test of each cylinder is probably in order. Or just skip all the diagnostic nonsense and have it rebuilt.

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If you don't have one purchase a compression tester.

Repeat the compression test, and record the results.

Repeat the compression test again, but before testing each cylinder, squirt a couple of teaspoons of new engine oil into the cylinder through the spark plug hole.

Compare the results.

If the rings or valves are bad, NOTHING you do to the choke or carburetor are going to make much difference.

Jon.

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Stan, If it comes to replacement I have what I believe is a good S15 engine. According to what I am told it will go in any 1940 to 54 as if it belonged there.

It turns over freely, but that is all I know. I bought it with a bunch of parts for the 51.

Gary

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Several things:

1) Thanks Gary for the offer of your engine. If it comes to something this costly, I'll slit my wrists. (Either that or cut my losses).

2)A very competent mechanic, who knows about old cars, did the compression test, with the following results: 1st cyl: 65 psi; 2nd: 45 psi; 3rd: 10 psi (35 w/ oil); 4th: 10psi (25 w/ oil); 5th: 20 psi (35 w/ oil); 6th: 30 psi (45 w/ oil). I'd hope, CarbKing, that this guy did the things you recomended.

3) Maybe, Jim Edwards, having it rebuilt would be the best course. Can someone tell me how much this might cost - one thou, two etc??

4) Finally, I think I'll post future references to this ongoing saga only here in "Technical" forum, rather than here AND in the DeSoto section.

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Stan - my chart shows a fresh engine at about 120 per cylinder. A good engine 80~90.

I wouldn't even try to do anything except rebuild/replace the engine if any were below 60. Just my opinion, others may differ.

Jon.

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Several things:

1) Thanks Gary for the offer of your engine. If it comes to something this costly, I'll slit my wrists. (Either that or cut my losses).

2)A very competent mechanic, who knows about old cars, did the compression test, with the following results: 1st cyl: 65 psi; 2nd: 45 psi; 3rd: 10 psi (35 w/ oil); 4th: 10psi (25 w/ oil); 5th: 20 psi (35 w/ oil); 6th: 30 psi (45 w/ oil). I'd hope, CarbKing, that this guy did the things you recomended.

3) Maybe, Jim Edwards, having it rebuilt would be the best course. Can someone tell me how much this might cost - one thou, two etc??

4) Finally, I think I'll post future references to this ongoing saga only here in "Technical" forum, rather than here AND in the DeSoto section.

The cost of a rebuild depends upon a number of things. But the first step will be to remove that engine from the car, disassemble and determining whether the block is cracked. Cracked block, game over. Not cracked it needs to be determined how much boring if any is required. Something no more than .030 over original specs is not a big issue. Beyond that you are looking at determining piston and ring availability. You won't likely get out for under $2,000 to $2,500 under the best of circumstances, which means a good running used engine with good compression is probably the best choice.

If it were me, I would be doing the latter. An engine with such low compression on all cylinders is likely going to be a lot more costly to fix, assuming it can be fixed. Take Gary up on his offer if he's near enough to get the engine he has without it being a super big deal. As he said, the engine from an S15 is the same. The engine type continued on with other Chrysler products well into the late 1950s and any of them will do just fine.

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Stan - Just a thought or so on this engine. With the compression #'s that you stated a leak down test not worth the effort. As would be setting #1 cylinder up on compression stroke at top dead center and checking where the rotor is point in the distributor cap as this would determine if the timing had skipped a tooth or so. Looks to me like you are in for a complete overhaul of this motor. If this is a #'s correct car and you want to keep it that way then the complete overhaul is the cost of keeping it that way. As stated by others the parts for this engine are still readily available at reasonable prices. If you do the removal and install on the engine you will save yourself some of the total cost of the repair and know that those jobs were done right. If the car is just a driver then a used replacement is the way to go. Remember these old engines didn't get really high mileage without some sizable problems internally. My dad was fond of Chrysler Corp flathead 6's. His were the 40's and 50's versions in Plymouths mostly,so we had our share of experiences with these engines. Be sure to check the distributor shaft for wear whichever way you decide you to, go complete overhaul or used engine. These shafts seemed to be a constant source of trouble until replaced in the cars he had. As I said just some thoughts from my experiences. Mark

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  • 1 month later...

LATEST UPDATE: Just found a competent mechanic who is willing to take on this project, not too far from home. Hopefully, this will be the last time I'll need to have her (expensively) towed (on a flatbed). In an hour & a half, we'll bring her to his garage, & begin the diagnoses. I'll of course pass on to him all the advice you've given.

Stay tuned . . .

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  • 4 weeks later...

here''s the final, sad, chapter: Following the advice of a member who advised that rather than subjecting the car to possibly lengthy & expensive diagnostics, & to just get a new engine installed, a mechanic estimated that it may cost $5,000. minimum to get the new engine in. So I decided to sell the car.

Since these old ('50's & earlier?) engines had serious problems after a few tens of thousands of miles, (although I've heard good things about the 40's & 50's Buick straight eights), I'll probably look for a car with as low miles as possible in the future.

thanks again

ss

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Well lets start again. Did the car the last time it ran, run well, idle smoothly, have good oil pressure and not knock or burn lots of oil? You said it ran good-your'e sure?

Did the car have two year or older gas in it? Because if it had old fuel in the tank I have seen and had it happen-this old varnish gas will cause the valves to sick and not close completely.

It usually happens after a good drive. Park it for a day or a week and next time you try to start it it won't or will have a pretty good pounding miss.

Your'e mechanic needs to pull the head and check the valves for proper operating/seating action. Maybe he just is not motivated enough? Pull the head or tappet chamber covers and you check for sticky /hanging up valves. All this assuming this engine was strong and did run well during your'e last drive..

Another note the timing chain can easily be checked for wear by rocking the crank back and forth and watching for delayed rotor movement.

A shot of a 1950 Chrysler worn out chain with 110,000 miles. Car ran well.

http://img819.imageshack.us/img819/2134/1950chryc48worntimingch.jpg

Bob

Edited by c49er (see edit history)
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Stan--Whoa, wait a minute here. Any competent mechanic of older cars should be able to give you the bottom line diagnosis in about 1 hour for around $100.00 depending on the part of the country you live in with a few simple tests. I believe the figure you mentioned is high even if the motor had to be completely rebuilt with all new parts. It's you car and your call but I'd get a second opinion or three before I threw the baby out with the bath water so to speak. Just my two coppers worth. Good Luck, Mark

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I can be stupid sometimes, but this was my first foray into trying to have serious diags/repairs done on an antique car. True, I probably should've gotten other mechanics to look at it, but with the 3 who did look at it, it was getting expensive to keep having the car flatbedded to and fro.

On a personal note, I've ALWAYS loved antique cars (who knows why), & have spent the better part of the last 40 years salivating over them. Of the 2 I've previously owned before the Desoto, the 49 Buick Super I had to sell to afford a house, & the 53 Bel Air was totaled in a tragic crash in which the other (uninsured) driver was 100% at fault & was arrested on the spot.

Now, the expensive lesson I've learned is to FIND A COMPETENT MECHANIC. Reputation, I'd say, is paramount, since they " . . . cant tell how much up front the repairs will cost, until everything's apart, etc.,", which by that time, they pretty much have you over a barrel. I live in Concord, New Hampshire, & if anyone knows of anyone, please tell me.

Thanks Mark, & Bob, your photo of the timing chain didn't look like there was significant wear (though I probably wouldn't know what to look for).

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Hi Stan,

That timing chain picture shows a really worn out chain. The car ran good but was a little sluggish. After the new chain install all was good. I'm not saying yours is bad either. I have never seen a chain jump on a Mopar flathead. I suppose it could, just never seen it happen. Done a ton of rebuilds on them too.

1950c48chryslerwornchai.jpg

Bob

Edited by c49er (see edit history)
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You're going to have to practically give the car away if it doesn't run, no matter how nice the rest of it is. You will have a hard time selling it for any price, and I doubt you'll come out ahead in any way, shape, or form by just dumping it with a bum engine.

Fixing it (and $5000 is A LOT for a rebuild on that particular motor) will add value and allow you to enjoy it. You should be able to find a machine shop that can rebuild such a simple motor relatively inexpensively, and parts are all available from Egge. Find a good engine machine shop and have them give you a quote. I think you'll be surprised how reasonable it can be. It's also relatively easy to get it in and out of the car, even for a novice.

Don't be intimidated, get in there and get dirty!

PS: Don't be afraid of mileage. These old engines ran for 100,000 miles and are just as good inside as modern engines. Trying to find an old car with low miles is going to be tougher than you think. Trusting the odometer on an old car is always a mistake.

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Thanks folks. I should've been more explicit. I already sold the car a few days ago - for $2,000. You're right - I lost a lot of money.

I'll do my HW first & make SURE there's a good mechanic/machinist in the Concord NH area before buying another antique car (anyone know of any?)

One more question before I buy another: Is a tired engine (one that strains or wont go much over 50 mph) a sure sign that if I was to use the car as a daily driver, it would soon need major engine work?

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Thanks folks. I should've been more explicit. I already sold the car a few days ago - for $2,000. You're right - I lost a lot of money.

I'll do my HW first & make SURE there's a good mechanic/machinist in the Concord NH area before buying another antique car (anyone know of any?)

One more question before I buy another: Is a tired engine (one that strains or wont go much over 50 mph) a sure sign that if I was to use the car as a daily driver, it would soon need major engine work?

It could be a worn out engine or it could just need a tuneup.

For your purposes I suggest you look at cars from the sixties or newer. No older than the mid to late 50s. They come with OHV V8 or six cylinder engines, automatic, etc and are generally longer lived than the older models.

If you are not mechanical it would pay to have a car checked out by a good mechanic. And to pay the price for a good car, either a well preserved low mileage model or one that has been repaired properly. Would also suggest a Chevrolet would be the safest to buy, as they have the best parts backup and there are lots of mechanics who understand them.

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Yes, I agree, the DeSotoStan moniker will have to go.

Thanks, Rusty OToole for the advice. I couldn't agree more - except, I have also been considering Fords (specifically the Galaxie). My requirements are 1)Automatic transmission,& 2) (hopefully) 6-cylinders. I intend to drive it daily, & with gas prices what they are, a V-8 could be costly. I also understand that I'll need to spend some good money for a car in great condition. (A convertible would also be nice.)

Will keep updating.

ss

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Hi everyone, I bought Stans Desoto. I got it to fire, but not run. Spark was not consistent so I pulled distributor and adjusted, filed points and put in a new condensor. Still not running so yesterday I pulled the head, haven't looked closely yet but I don't see anything that stands out that is wrong--no holes in pistons or anything like that. I really need more time to see if I can figure out what is going on. I am going to check the head and see if it is warped and clean things up to start--I will update when I know more--

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Could be the coil. I'd put a 12 volt in it and crank er up. Valves won't cause a weak spark. + sde to the distributor(ground). Make sure the wires in the dist. are good and proper too.

Bob

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Yes, I agree, the DeSotoStan moniker will have to go.

Thanks, Rusty OToole for the advice. I couldn't agree more - except, I have also been considering Fords (specifically the Galaxie). My requirements are 1)Automatic transmission,& 2) (hopefully) 6-cylinders. I intend to drive it daily, & with gas prices what they are, a V-8 could be costly. I also understand that I'll need to spend some good money for a car in great condition. (A convertible would also be nice.)

Will keep updating.

ss

Stan (without the DeSoto) - a compression tester can be one of your best friends! Acquire one, and learn to use it BEFORE your next purchase.

Personally, I have ALWAYS purchased the shop manual and read it cover to cover at least twice before the purchase of any old car. You would be surprised at just how much headache you can eliminate by this trick.

And just for the record, if you require an auto trans, you MAY find that an eight cylinder will actually get better fuel economy than a six (depending on your driving habits). An automatic transmission devours power in doing the fluid coupling. The eight may have sufficient extra power over the six to be more efficient. Do a Google search on power loss through automatic transmissions. The figures may astonish you.

Jon.

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Dropped off the head this morning and here are the results--magnafluxed, no cracks. The machinist said that the head had a "funky twist" in it and he had to take off .012 (twelve thousands) to make it flat. Will check on the valves etc this weekend. I ordered a new head gasket.

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48 DLX I suggest you measure the taper of the cylinders. If it is .007 or less you can cut the ridge off the top, hone the cylinders and install new rings. Also grind the valves or replace if necessary. Check the bearings and replace if necessary. This can all be done with the engine in the car, it is called a ring and valve job and used to be a common type of overhaul. If the engine is not too badly worn this will give you another 20000 to 50000 miles of service. Provided the crankshaft, and cylinders are not too worn. If you had good oil pressure before you tore it down you should be OK.

If you really want to go first class you can pull the engine, tear it down and do a complete rebuild but the ring and valve job is an economical and perfectly satisfactory alternative, provided the engine is not completely worn out.

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