| Author |
Message |
    
Bob Dunne
New member
Username: bobct
Post Number: 1
Registered: 10-2009
| | Posted on Monday, October 12, 2009 - 06:26 am: | 
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I just bought a 1988 Trojan mid cabin a few weeks ago, twin 454's FWC. I've been going through the boat, fixing a bunch of stuff and putting together my winter list.
Over the weekend, I was working on the throttle cables and removed the two bolts that hold the cable bracket to the top of the intake manifold. I noticed that one of the bolt holes had coolant inside the hole. I did the same thing on the other engine, both were dry.
I thought that didn't seem right but buttoned everything up and took it for a test run. Over 2,500 rpms's it starts to stutter and sounds like it's misfiring.
I "think" it might also be throwing more steam out of the exhaust but running around 180F. Both engines steamed during the sea trial but never went past 180. I'm planning on doing elbows/risers and raw water pumps when it comes out in a couple of weeks.
Below 2,500 it ran fine.
It also did this last week when I took it out. It was a total coincidence that I was working on the throttle cable and removed the mounting bolts and saw what I did.
Yesterday, I noticed that a couple of the plugs wires were loose including the coil wire. I re-seated them, started it, and after warm-up, idled it past 2,500 at the dock and it sounded great. Not sure how it would be under load though.
I checked the oil and it looks fine.
I guess my question is, does the fact that I see coolant inside the bolt hole mean I have a problem? If so, would that be the intake manifold gasket?
thanks,
Bob |
makomark
Senior Member
Username: makomark
Post Number: 1646
Registered: 09-2008
| | Posted on Monday, October 12, 2009 - 09:18 am: |
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ignition wires highly suspect for the high speed miss.
Fluid appearing where it doesn't belong is a message - something needs correction. I doubt it to be the gasket. Do a thorough inspection and look for "drip trails" at all connections...when warmed up, that stuff can be like a kid and a hose; it goes everywhere.
A pressure tester is also handy for finding the source of the leak. If the leak is minor (< 1 qt/month) it may be hard to find. As long as it is not getting into the crankcase, it should be serviceable. |
Bob Dunne
New member
Username: bobct
Post Number: 2
Registered: 10-2009
| | Posted on Monday, October 12, 2009 - 09:48 am: |
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big omission in my post... I don't think I have a leak. I just happened to notice the coolant in what I thought was an odd place. It's not leaking past the bolt and the level isn't dropping.
I'm not sure if that's an indication of a real issue or that it's ok for coolant to be up in that part of the intake manifold. I didn't see it in the other three bolt holes (2 on the other engine and one other this one).
If ok, maybe the level is slightly higher on the engine in question?
I might have fixed the mis-fire issue with the plug wires, it certainly sounded good at the dock.
Bob |
makomark
Senior Member
Username: makomark
Post Number: 1647
Registered: 09-2008
| | Posted on Monday, October 12, 2009 - 11:03 am: |
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coolant shouldn't be in the blind holes. It mmay have been spilled during a top off or a check when the cap was removed.
either way, I'd keep an eye on it to see if it persists. |
Bob Dunne
New member
Username: bobct
Post Number: 3
Registered: 10-2009
| | Posted on Monday, October 12, 2009 - 11:14 am: |
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I don't think it could have spilled in past the bolt, maybe during some prior work. Both the Heat exhanger cap and overflow fill are at least a couple of feet away.
Maybe I should remove the bolt in question and crank it over, see if coolant shoots out?
Would you suspect a bad intake manifold gasket? It was changed at some point, it looks new(er) than the other side.
Would a bad exhaust manifold cause coolant to get up into the intake manifold? Again, no visible leak. It was just dumb luck that I happened to remove this bolt, otherwise I never would have known.
thanks for your replies...
Bob |
danny
Member
Username: lugnutdan
Post Number: 36
Registered: 02-2009
| | Posted on Monday, October 12, 2009 - 11:27 am: |
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The miss fire i also believe it would be the wires if it keeps doing it under load check the
firing order ,and if its steaming flush the u-coolers with muratic acid flush,did this with mine,took care of the steam and cooling. |
Bob Dunne
Member
Username: bobct
Post Number: 4
Registered: 10-2009
| | Posted on Monday, October 12, 2009 - 11:54 am: |
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here's a pic |
makomark
Senior Member
Username: makomark
Post Number: 1649
Registered: 09-2008
| | Posted on Monday, October 12, 2009 - 12:24 pm: |
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bob
I got a bit confused and you picture cleared that up. Those two bolts are on either side of the coolant crossover passage. I can't remember if the threaded holes in the cylinder head are open or blind. Maybe another member that has ready access to a cylinder head can chime in.
If they are blind, the gasket is leaking. If the holes are open, I'd expect to see coolant with the bolts out. Hard to tell but it looks like the 'upper' hole is wet, too. |
diver dave
Advanced Member
Username: diver_dave
Post Number: 456
Registered: 08-2008
| | Posted on Monday, October 12, 2009 - 12:42 pm: |
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I don't recall seeing coolant in that hole before, and am sure that the head is not drilled thru. You may get lucky and be able to use a copper sealing washer there and call it a day. If that doesn't work, that intake is coming off and check for erosion, bad gasket, or crack. |
Al
Advanced Member
Username: knuckle47
Post Number: 717
Registered: 09-2007
| | Posted on Monday, October 12, 2009 - 01:36 pm: |
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This is the exact same problem I thought I had. Enough so that it was filling up the valleys in of the intake manifold. Turned out ot be a hose problem that re-deposited the coolant on the intake.
I had my intake manifold off only last year and I do not remember those two holes being open. Can you stick a wire hanger down there to see how deep it may be? |
Bob Dunne
Member
Username: bobct
Post Number: 5
Registered: 10-2009
| | Posted on Monday, October 12, 2009 - 02:59 pm: |
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interesting, I'm going to head back later today and I'll put something down the hole. I actually have a borescope but not sure what I would see.
I took it out for a test run and it did the same thing under load. Once over 2,500 its started sputtering so I backed off. Positive it's not the firing order as I've been in the boat at WOT during the survey and nothing has been done since.
I'm wondering if I re-seated the cap wires which is why it sounded great at the dock and then they loosen up again underway. Is there better/more positive lock on a marine cap/wires?
This might be just an automotive set but saying that not really knowing if there's a difference.
The other variable is my fuel tank switchover. I stumbled across it last week and when I turned it, than handle broke so I have to re-tap the hole. I used a pair of pliers to put it back to where I thought it should be. It took me a few minutes to figure it out, I recall it wasn't as obvious as you would think. I forgot I did this but noticed one gauge reading lower than the other today. They were dead on SO maybe it's in the wrong place and I'm running on one tank now.
I assume that shouldn't change the driveability but could have introduced another variable.
I'm hoping that the coolant isn't running into the engine and causing my issue. I also going to pull some plugs as well. |
Rick Sweeten
Senior Member
Username: linesix
Post Number: 1590
Registered: 11-2002
| | Posted on Monday, October 12, 2009 - 03:11 pm: |
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That is a gasket. Right now it's only leaking into the bolthole but I would change it before it starts leaking into the runner.
It is probable just from loose intake bolts but if I were working on a winter list, this would certainly be on it. |
Bob Dunne
Member
Username: bobct
Post Number: 6
Registered: 10-2009
| | Posted on Monday, October 12, 2009 - 03:13 pm: |
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ok, so you would change the intake manifold gaskets? That's ok, I can handle that.
I'll pull some plugs, maybe the 2 issues are completely unrelated.
thanks,
Bob |
Rick Sweeten
Senior Member
Username: linesix
Post Number: 1591
Registered: 11-2002
| | Posted on Monday, October 12, 2009 - 03:24 pm: |
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Yes I would. Even if you're not loosing coolant yet, you soon will be.
Mark is right about the pressure test. It will tell you for sure. |
makomark
Senior Member
Username: makomark
Post Number: 1654
Registered: 09-2008
| | Posted on Tuesday, October 13, 2009 - 01:33 pm: |
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I knew the "been there..." crew would come thru. |
