>Ok gods of all things OD.. Here is the situation on the
>251 Canadian. Still would not run, had a friend over that
>has 5 M37's that all run and knows a little bit about them.
>We ran through all the normal checks. Good spark, got
>fuel,timing set right,plug wires right,and so on. Decided it
>may be the vaccum thing Charles mentioned awhile back. I had
>to just forget about the truck for a bit out of
>frustration,anyway #1 45lbs, #2-43 lbs, #3-NOTHING?? #4-
>45lb's, #5-45lb's,and #6 54 lb's.
>Exhaust valve on #3 is stuck! Whats the best way to un-stick
>it? I took a piece of hardwood and tapped very gently and
>nothing. Is there a good product that I can put down the
>cylinder to eat away bad gas residue? Do I have to pull the
>head? Next step please?
>Could this be the reason it will not run again? Not enough
>vacuum for fuel adimizing? Uhhh...It seems like it would
>fire if even just run like pooooo... How are these
>compression readings? Are they to low?
>
You need not expect it to run with low readings like this. The stuck valve is the least of your problems. To run good, you'll need at least 100+ PSI at every cylinder. Less than 90 probably won't run at all or will be skipping & very rough. You need to investigate further to see what the deal is that is causing low readings. Pour a tablespoon or so of oil in the plug hole & re-test each cylinder (pouring in the oil 1 hole at a time just prior to testing each cylinder.) If you get a significantly higher PSI reading after the oil is induced, that would indicate that bad piston ring seal is the cause of the low readings. If you get little or no change in the reading after pouring in the oil, that would indicate the problem is the valves. Since you've established that 1 valve is stuck, you may have others that are partially stuck causing these low readings. Once you get the result of the 2nd test, you will then need to follow the indicators you get in order to correct the problems. If it's rings, you are facing a complete overhaul, if the indicators point toward valves, you may as well do a complete valve job. You are most definitely faced with 1 or the other based on the information you have given.
www.mseriesrebuild.com
Charles Talbert
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citizensoldier
unregistered user
01-Jul-06, 09:09 PM (pst)
2. "RE: Compression readings extremely low"
In response to message #1
Hey Charles! Your up late.. I was hoping to get a response from you. I will perform the test you mentioned tomarrow. It doesnt look good does it? Do you still have that 251 Canadian military block? At one time you said you had one laying around the shop. I was looking for a manifold set at the time but they were gone. How much to rebuild it and ship a "short block" to Michigan?
Hardened valve seats, boil and bore, check crank, new cam, pistons,rings,head milled,new valves and so on..The works.. for the block anyway?
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MSeriesRebuild
Member since 3-Aug-04
1461 posts 01-Jul-06, 09:26 PM (pst)
3. "RE: Sorry, no 251 at this time"
In response to message #2
Don't have anything to offer right now except 230's. For us to go through yours like you described, I'd say $2,000-$2,500 range, depending on how bad it may be or if any major parts were not usable & had to be replaced.
www.mseriesrebuild.com
Charles Talbert
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citizensoldier
unregistered user
01-Jul-06, 09:40 PM (pst)
4. "RE: Sorry, no 251 at this time"
In response to message #3
Any idea on freight? Thanks for the reply... You have been a great help and I appreciate it very much.
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MSeriesRebuild
Member since 3-Aug-04
1461 posts 02-Jul-06, 10:02 AM (pst)
7. "RE: Sorry, no 251 at this time"
In response to message #4
>Any idea on freight? Thanks for the reply... You have been a
>great help and I appreciate it very much.
Freight rates have taken a giant leap as you might expect with fuel cost increases. You would have to call your local motor freight co. for a quote since you would be the shipper.
www.mseriesrebuild.com
Charles Talbert
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citizensoldier
unregistered user
02-Jul-06, 08:46 AM (pst)
5. "RE: Compression readings extremely low"
In response to message #1
Second test #1=70 Psi, #2=65 Psi, #3=0 Psi, #4=70 Psi, #5=65 Psi, #6=55 Psi.
What do you think? Is this little difference bad valves or am I in for the big one?
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MSeriesRebuild
Member since 3-Aug-04
1461 posts 02-Jul-06, 09:58 AM (pst)
6. "RE: Compression readings extremely low"
In response to message #5
>Second test #1=70 Psi, #2=65 Psi, #3=0 Psi, #4=70 Psi, #5=65
>Psi, #6=55 Psi.
>What do you think? Is this little difference bad valves or
>am I in for the big one?
>
Leaking rings will usually be sealed by the oil which generally makes for significantly higher readings. Based on this information, I would further investigate for valve issues 1st. If the engine has been run even for a few minutes on stale gasoline, that is enough to do the valves in, what you are describing sounds like an all too familiar story. I say again, I could never make a solid diagnosis unless I could check it myself, sure sounds like valves to me though.
www.mseriesrebuild.com
Charles Talbert
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citizensoldier
unregistered user
02-Jul-06, 10:12 AM (pst)
8. "RE: Compression readings extremely low"
In response to message #6
Thats what I was thinking but I was unclear on "siginifant difference"? Well it wouldnt hurt to pull the head and do a valve job on it. If it turns out to be the rings then I will yank her out and have it rebuilt.
I bought this truck out of Canada and put fresh gas in it and ran it for a little bit before changing the manifolds. It did have bad gas in it though because the tank was a mess. I just had it Re-newed but it was too late... Oh well I learned the hard way on this on...
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Lifer
Member since 4-Aug-04
1140 posts 02-Jul-06, 11:26 AM (pst)
9. "RE: Compression readings extremely low"
In response to message #8
"Lessons learned the hard way are lessons best remembered," they say. At least you aren't pouring money down a hole by looking for the "quick and cheap" fix that doesn't exist. Go ahead and do whatever mechanical work is required and enjoy yourself doing it. Then, let the wife worry about the expense. After all...that's her job!
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powool
Member since 9-Aug-04
95 posts 03-Jul-06, 04:14 PM (pst)
10. "RE: Compression readings extremely low"
In response to message #8
I'm very interested in hearing your experience in valve tweaking - I'd like to see if my 230 can be brought back to life (even if just a summer) by some modest valve work (as opposed to an engine swap or full engine teardown).
Paul Anderson
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doodlebug
Member since 15-Jun-06
37 posts 03-Jul-06, 04:17 PM (pst)
11. "RE: Compression readings extremely low"
In response to message #6
Just curious. I'm not all that familiar with the flat head sixes, but does the engine have to be pulled to do a valve job, or can it be done in the vehicle?
Ron
1962 M37B1
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dr9487
Member since 1-Aug-04
901 posts 03-Jul-06, 05:02 PM (pst)
12. "RE: Compression readings extremely low"
In response to message #11
It can be done in the vehicle. You can take the valves to be done, but you need the correct tool to resurface the seats in the block. if they`re in good shape, you may be able to lap them in with valve grinding compound.
Rick
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citizensoldier
unregistered user
03-Jul-06, 05:51 PM (pst)
13. "RE: Compression readings extremely low"
In response to message #12
Well I am just going to dust off the manual and give her a go. I do have the correct tools for the seats. A complete set came with one of my buddies parts purchases. What I dont have is the special valve spring compressor. I guess I have to pull that **** manifold set off again! This will make the third time.
Any of you guys have a valve spring tool you will loan me? I will pay shipping both ways..
Also if any of you pro's want to share some secretes on doing this feel free to have at it! This is new territory for this shade tree mechanic.
Can the valve seats be changed with the engine in the truck? I wonder if I should have harnened seats put in if that is possible? If not it should last for a little bit shouldnt it? There is alway lead additive I guess..
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dr9487
Member since 1-Aug-04
901 posts 03-Jul-06, 06:29 PM (pst)
14. "RE: Compression readings extremely low"
In response to message #13
When you pull the head, look at the valves good. Spray penetrating oil around the guides and roll the engine. Make a note of any that don't close all the way. Tap them lightly as you turn the engine to get them working all the way. If they free up easy, you might get by with just a new head gasket. TRY THIS BEFORE YOU PULL THE MANIFOLDS!
Either way, you need to get them working so you can pull them out of the guides to take the valves out. I've had good success doing this on vehicles with stuck valves over the years. Good luck.
Rick
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brianacarey
unregistered user
03-Jul-06, 08:08 PM (pst)
15. "RE: Compression readings extremely low"
In response to message #13
Lane,
I might have a valve spring tool that will work. It is a big U shaped thing. I will send it if you want it, but I don't think they are that expensive. I bought mine at Sears for about 30 if I remember right. It might not be the best tool as I know some people have a lot better ones, but it worked for me. I have not used it on an M37. Let me know.
Jason
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Lifer
Member since 4-Aug-04
1140 posts 03-Jul-06, 08:25 PM (pst)
17. "RE: Compression readings extremely low"
In response to message #15
The "big U-shaped things" are for OHV engines with the valves in the heads. It has to go around the head to apply pressure to the springs. For flatheads, you need the "pliers" type.
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dr9487
Member since 1-Aug-04
901 posts 04-Jul-06, 05:20 AM (pst)
19. "RE: Compression readings extremely low"
In response to message #17
With the manifolds off, the U shaped one should work on a flathead as well. It may work better because it would give more room around the keeper area.
Rick
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Lifer
Member since 4-Aug-04
1140 posts 04-Jul-06, 06:20 AM (pst)
20. "RE: Compression readings extremely low"
In response to message #19
You have a point, there! Those "pliers" type spring compressors are a real pain to work with - even with the engine out of the vehicle where everything is "easy" to get to.
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BILL L
Member since 2-Aug-04
435 posts 04-Jul-06, 07:49 AM (pst)
21. "RE: Compression readings extremely low"
In response to message #15
This is what the correct original valve spring compressor looks like.
Attachments
http://www.g741.org/dcforum/User_fil...0873b4a933.jpg
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Lifer
Member since 4-Aug-04
1140 posts 04-Jul-06, 09:28 AM (pst)
22. "RE: Compression readings extremely low"
In response to message #21
Thanks, Bill. I knew somebody had to have the right one.
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brianacarey
unregistered user
03-Jul-06, 08:10 PM (pst)
16. "RE: Compression readings extremely low"
In response to message #13
Lane,
Here is the address of the one I have. I am sure people have better, but it might work.
http://www.sears.com/sr/javasr/produ...seBVCookie=Yes
Copy and paste.
Jason
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MSeriesRebuild
Member since 3-Aug-04
1461 posts 03-Jul-06, 08:59 PM (pst)
18. "RE: Valve spring compressor"
In response to message #13
You can get a correct reasonably priced valve spring compressor for use on L-head engines at NAPA. There is a possibility you could unstick them, but you can't do a proper clean up job in the guides with out removing them. The job is much easier if the manfold assembly is removed. It's also very easy to spot leaking valves, if the manifolds are off. The test will need to be done at night or in a VERY dark area during the day. Rotate the engine to TDC at compression when both valves would be closed on any cylinder. Turn off all lights, place a good lighted flashlight tightly against the intake port, then the exhaust port for that cylinder. If there is even a slight leak you will see light around the head of the valve. Progress through all 6 cylinders with this test, based on the info. you have shared, I believe you will likely see the reason for the low compression problem. Valve guide bore brushes are available at NAPA to clean up the guides. Once they are clean, insert the valve back into the guide & check for proper clearance. If it's excessive in accordance with the specs. in the manual, you'll need to replace the guide & the valve. The exhaust seats are replaceable in the field with the correct tooling. High nickel hardened seats designed for use with unleaded fuel are available. The intake seats are not replaceable as the seat is machined into the block deck. Machining can be done & new intake seats installed, but the engine block will have to be stripped & sent to an engine machining facility to perform this. The guides can be replaced in the field also, but you must have the proper guide drivers & reamers to perform this task. Guide reaming is a must after installation as in most cases the guides will mushroom slightly from the driving process. Trying to do this without reaming will likely cause you heartache. If you have to use force such as a puller to remove the valves, forget trying to re-use them, they will be warpped. Do it right, do it once. If I can help with further questions, feel free to give me a call at the shop, 704-474-4683.
www.mseriesrebuild.com
Charles Talbert
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powool
Member since 9-Aug-04
95 posts 04-Jul-06, 07:27 PM (pst)
23. "RE: Valve spring compressor"
In response to message #18
I have read more than once that an intake valve would not normally need the hardened seat, since it usually runs at lower temperature. Do you feel this would be the case for the 230 as well? The context I've read that in was only for OHV engines, not L heads.
Paul Anderson
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MSeriesRebuild
Member since 3-Aug-04
1461 posts 05-Jul-06, 09:34 AM (pst)
24. "RE: Exhaust that takes the beating"
In response to message #23
This is pretty much the case as far as the bare necessities go. I would definitely change out the exhaust seats at rebuild time, no question. I guess I would say depending on how the truck will be used might determine the intake seats. If it's a hobby truck that will see few miles for many years, it would likely be OK to re-surface the intake seats & install new valves. If it's a truck that will see daily or frequent use, I would recommend doing them all while the block is in the machine shop at rebuild time. Doing the necessary machine work to install intake seats is to big of a job to tackle except at rebuild time unless you have a situation that makes it absolutely necessary.
www.mseriesrebuild.com
Charles Talbert
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RE: stuck valve
