Blown Head Gasket?

[NoName]

First of all, I had to change my login name to even get on the forum. Second, the search is disabled so I have to ask this question. (Now that I've got my gripes out . . . ) I've got a Ford 203/888 Merc with an over-heating problem. It's raw water cooled, no power steering, working impeller. I've had the risers off, mans opened & cleaned, all hoses off, new thermostat. My mechanic says he might suspect a bad head gasket and it needs a cylinder pressure test. He said that this would cause poor water circulation. Does this sound logical?

 

[Gary H NC]

Re: Blown Head Gasket?

To get your display name back,go to My user area and just change your nick name...
Your overheating problem: I would have the leakdown test done before tearing into the engine.
A bad headgasket is very much a possibility..

 

[lilmandavis]

Re: Blown Head Gasket?

whats it timed at? does it overheat at idle, mid-range, wot?

 

[NoName]

Re: Blown Head Gasket?

It overheats at any RPM. Here's how it all started. This spring everthing was fine, After a few weeks, however, it started to heat up in the no wake zones. But once back on plane, it cooled down. It's progressively gotten worse, and now, I can't go 500 yards without it overheating.

 

[Gary H NC]

Re: Blown Head Gasket?

A leak down test should tell the story...

 

[hullofalottatrouble]

Re: Blown Head Gasket?

do a compression or leakdown test.. could be a lot of things.. compression test is easy enough and should give ya pretty good indication of a blown head gasket.. id start with that before tearing into the thing..

a blown head gasket can results in poor water circulation as it can force tons of hot air into the system.. dont want air in there..

 

[northvanwatertaxi]

Re: Blown Head Gasket?

unplug the hoses to the riser and use a garden hose to see if the they are plugged if the hose swells up that could be the cause

 

[Haut Medoc]

Re: Blown Head Gasket?

I doubt that a blown head gasket would cause an overheat condition on a raw water system....
Maybe on a closed system, cause the exhaust gas has no where to go, but with a raw system it would be expelled with the cooling water...
In your other post, you said water gushes out of the inlet hose.....
How much water is coming out at the drive end?
Are you equipped with a vacuum gauge?
Have you done a vacuum test to check for an exhaust restriction?
Like a broken exhaust flapper stuck somewhere?
Do the compression test, but the vacuum gauge will tell you more & be easier to do initially.....
I doubt that you have a blown head gasket.....JK

 

[NoName]

Re: Blown Head Gasket?

Broken exhaust flapper, eh? That was my original thought because the motor runs great. I get 30 MPH at 3000 RPM. It idles fine and stays on plane at 2000 RPM. I don't see how I could have a blown head gasket. My problem is that I don't find a reference to the flapper in the manual. I've seen photos of a broken/lodged flapper on this forum, but not in the repair manual. Either way, it's coming out of the water this week for a leak down/compression test.

 

[Haut Medoc]

Re: Blown Head Gasket?

By all means run the comp. & leakdown tests....
A vacuum test will tell you if you have an exhaust restiction or a leaky intake manifold though....
What manual are you using? You should have Merc. 1 or 2......JK

 

[NoName]

Re: Blown Head Gasket? Update!

Re: Blown Head Gasket? Update!

The leakdown test will be later this week. I pumped some oil out of the thing -- no milkyness, no water droplets on dipstick. I'm thinking not a head gasket. So I pulled the water hose off the manifold, leading to the thermostat housing, and started the motor. Water shot 10 feet in both directions! MAJOR smell of exhaust coming out. Every hose I pulled off did the same thing. So, I'm thinking there's a major restriction in the exhaust pipe. Am I right?

And Jammer, I'm looking at the manuals at boatfix.com, but there's no 1 or 2 listed. The only hard-copy manual that I have is the Selock. So far it's been good for wiping the oil off my hands. And it says that I have to pull the motor to fix the flapper. :%

 

[Haut Medoc]

Re: Blown Head Gasket?

I would be more concerned with getting a broken flapper out than fixing it.....
You don't really need the flappers, they are there as a precaution to keep water from backing up into the cylinders......
The only time I would worry about that is a dead shutoff from high speed.....
Which you should never do....
If you gradually back down to idle before shutting down, it should not be a problem....
Pull the drive off, if you can't do a vacuum test.....
Look in the exhaust bellow & the drive itself for the flapper.....
They are down at the bottom of the Y-pipe, so in order to fix them the engine & y-pipe would have to come out.....
Not worth it, IMHO......
At least not until you repower.....
Keeep your eyes open on ebay, those manuals do turn up occasionally.....
Well worth the effort to find one, they are very comprehensive.....
What make of boat is this in, btw?......JK

 

[NoName]

Re: Blown Head Gasket?

Hey, thanks for the advice. The boat is coming out of the water on Saturday,so I should have a the answer by that afternoon. It will be my first time pulling a drive off. I'm looking forward to it. I'll post an update to show what I found.

The boat is a '72 Winner -- 19 foot runabout. I have a website with some pics.
http://www.normrogers.8m.com/boat.htm

 

[Haut Medoc]

Re: Blown Head Gasket?

Grease the ujoints while you have it off.....JK

 

[NoName]

Re: Blown Head Gasket?

I'll have to pull the drive with my fingers crossed. Since I'll have it off, what should I replace in there besides the three bellows?

 

[Haut Medoc]

Re: Blown Head Gasket?

Pulling the drive a'int that big a deal....
Changing the bellows is....
If you are going to replace the u-joint bellows, then you should replace the shift cable, too.....JK

 

[Reel Poor]

Re: Blown Head Gasket?

And also check engine alignment. You will need one of these.

 

[achris]

Re: Blown Head Gasket?

I realise this thread is 18 months old, but did we ever find out what the problems was?

What nobody suggested was a leaking water pocket cover in the bottom of the upper driveshaft housing. When the cover distorts (it's only plastic), the gasket leaks and lets exhaust gas into the cooling system. Doesn't matter how good the water pump impeller is, exhaust gas in the cooling system = overheating at all speeds.

Chris.............

 

[Don S]

Re: Blown Head Gasket?

Good grief Chris, sure hope you don't want to know about every post that went on without a completion.
If you really need to know, send them a PM and ask.

 

[flabum]

Re: Blown Head Gasket?

It probably turned out to be a bunch of barnacles covering the lower unit.