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| Help with diagnosis - Chrysler Crown ... |
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brian_vancouver
New member
Username: brian_vancouver
Post Number: 2
Registered: 11-2013
| | Posted on Sunday, November 10, 2013 - 03:41 pm: | 
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I am having the following problem in a ~1949 twin carb, 6 cyl Chrysler Marine Engine, and would appreciate your idea(s) on its diagnosis.
I am getting coolant in two of the cylinders -- leaks/out through the plugs, mostly after the engine is shut-down. There is no coolant in the oil. It still starts and run reasonably well (obviously, I'm not running it now). I am thinking its a cracked exhaust manifold -- correct? Or??
I have to decide to either fix or repower her (Ouch $$) but want to confirm my "diagnosis" before I start spending a lot of money tearing down and repairing it,
Your help with the diagnosis would be appreciated,
Thanks,
Brian |
robert
Senior Member
Username: robert
Post Number: 624
Registered: 07-2003
| | Posted on Sunday, November 10, 2013 - 05:48 pm: |
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I don't understand "leaks out through the plugs", do you mean the sparkplugs or freeze/core plugs? If water can get out through your sparkplug holes then compression gasses must be doing the same.
Raw water cooled? Manifold and or gasket last replaced? Head gasket last replaced?
As for $$ that Chrysler must be a terrible gas hog, why not replace with a used diesel?
There was a very nice Perkins M6 here you could have had for $500. I think it was scrapped in the end. |
brian_vancouver
New member
Username: brian_vancouver
Post Number: 3
Registered: 11-2013
| | Posted on Sunday, November 10, 2013 - 06:50 pm: |
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Hello Robert,
Thanks for your reply.
Part of the problem here is that I'm not at all familiar with these engines.
The "leakage" is of coolant (anti-freeze) through the two spark plug holes (with the plugs installed) nearest the exhaust/flywheel end. I have found a corresponding external crack in the exhaust manifold at the same location. I have not pulled anything apart yet.
I'm not quite clear on the cooling loop(s)? It uses raw water to cool the oil heat exchanger and the exhaust. However, it also has a closed glycol coolant loop that routes coolant through pipes mounted under the boat. I'm not clear on which "system" cools what?
As I mentioned, there is no sign of coolant in the oil (tested); and based on the colour, it is clear that the coolant that is leaking up out of the two spark plug holes is glycol, not sea water.
One more thing, I have discovered that the oil heat exchanger is heavily blocked -- apparently from there NOT being a raw water filter on the sea water intake (geez!). The engine has been running hot.
As for mileage, it only burns about 2 gal (US)/hour so not bad.
I haven't yet started to seriously contemplate a repowering, but would obviously have to include the cost of the diesel, swap-out labour (not a job I'm skilled at), transmission, fuel tank, possibly the shaft and prop set-up. I can only imagine it being a costly undertaking.
This versus replacing the exhaust manifold (assuming that's the right diagnosis (??) and I can locate the part). I simply don't know enough yet,
Thanks again,
Brian |
robert
Senior Member
Username: robert
Post Number: 625
Registered: 07-2003
| | Posted on Sunday, November 10, 2013 - 07:03 pm: |
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Is it possible that the water/coolant is simply leaking out of the crack and running into the ports the plugs sit in, collecting there and giving you the impression it is actually leaking out around the plugs? (Assuming they are recessed into individual ports) Highly unlikely to be leaking out of the cylinders, water does not compress and if you have enough water in the cylinder for it to be pushed out around the plug, I think it's more likely your engine will come to sudden, loud stop, sometimes known as "hydraulic-ing" to off-roaders and other people who submerge their engines.
I suppose your first step should be a compression test to see if in fact there is an issue with one or more cylinders.
So you do have "keel cooling" for the engine coolant then; that's a plus. You should have at least a strainer on the raw water intake. An inboard filter would be easy to install, somewhere you can monitor it easily. A length of clear hose is always good to see what's flowing in or out.
Best bet would be to find the manuals online and study up, as well as investigating the service and running history you have on the engine, if any? |
brian_vancouver
Member
Username: brian_vancouver
Post Number: 4
Registered: 11-2013
| | Posted on Sunday, November 10, 2013 - 07:29 pm: |
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Thanks Robert,
I had thought about the possibility you mention, that the coolant is leaking "into"and pooling in the plug recesses from the outside. I can't find where it would be coming from though, there is nothing on top of the head (except the spark arrestor tube). I'll look again.
Something that may/may not support your idea is that the engine is burning very rich (my original intent was to have the carbs overhauled), so the plugs blacken up almost immediately after new ones are installed. Then pulling and examining the plugs shows no sign of "wetness" which would wash off some of the fresh black coating. Also, after running for a short bit with new plugs, both they and the piston top show no signs of any coolant/moisture. It only appears pooled around the plug recess a while after the engine is shut-down.
That said, I know there is a crack on the exhaust manifold so it still would need replacing if i can figure out where to get one.
As for the keel cooling, do you know what is cooled by the closed versus raw water loops?
Thanks for all of your help,
Brian |
robert
Senior Member
Username: robert
Post Number: 626
Registered: 07-2003
| | Posted on Sunday, November 10, 2013 - 09:35 pm: |
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Photos would help a lot of course, and save you time and money with mechanics probably.
Is it possible there is a pinhole leak somewhere which is squirting up onto the area affected, but is not obvious after the engine shuts down? Water doesn't run uphill, so hard to see any other options from what you describe.
Before you go to the expense of carb rebuilds you could try a couple of tins of Sea Foam in the fuel, and fill the fuel filter with it.
I don't think there is anything to add to what you have told us about the cooling system, except that the manifold may well be salt water cooled as well and that is what has caused the cracking perhaps. |
brian_vancouver
Member
Username: brian_vancouver
Post Number: 5
Registered: 11-2013
| | Posted on Sunday, November 10, 2013 - 09:50 pm: |
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Thanks again Robert,
You've given me a few more things to chase down.
I suspect the exhaust manifold is part of the closed loop. The crack leaked glycol. I'll take your advice on the carbs and will continue to dig around to see if I can locate a replacement exhaust manifold and gasket.
I'll also see if I can get a couple of photos posted,
Brian |
wrenchguy
Member
Username: wrenchguy
Post Number: 25
Registered: 03-2008
| | Posted on Sunday, November 10, 2013 - 10:10 pm: |
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get ahold of jim at finewoodboats.com, he knows those motors. |
brian_vancouver
Member
Username: brian_vancouver
Post Number: 7
Registered: 11-2013
| | Posted on Friday, November 15, 2013 - 10:00 pm: |
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Thanks -- I'll hunt down Jim.
I appreciate all the help guys,
Brian |
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