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I have a 1994 Betram Moppie 30.6 (so its not the classic 31 but looks a more like a Tiara 31). The engines are 1994 Crusader 7.4 XLi (throttle body injection) with almost 2000 hours. [The boat is on the Chesapeake Bay]

I figured I pull the exhaust manifolds (due to age) when I went to replace the risers and discovered a bit of rust in some of the exhaust ports.
[NOTE The boat hadn't been used for over a year]

So I'm looking for some advice on how to proceed. And recommendation for shops/yards to use.

Do I just slap on some new exhaust manifold and riser and see what happens or do things, based on my limit knowledge the "correct" way and pull the engines and recondition/rebuild/repower? And just as important what kind of budget would I be looking at to know what I can/can't afford:

Here is a link if your not familiar with the boat
https://www.yachtsurvey.com/boatreviews ... moppie.htm

I was also thinking of doing a compression test but haven't done that yet (hopefully this weekend when I can get a friend to help)

With my port motor I got a rebuilt block and reused many of the parts off my old engine. I continue to chase gremlins, it’s pretty darn frustrating at times. I recently replaced the starboard motor with a new motor built my michiganmotorz and she runs like a top. Wish I had done the same with the port motor. I have 454s but on their website you can see prices on all the motors

26 years old and 2000 hours and you say you have some rust on the exhaust ports...

I may get flamed for this, but in my opinion, if motors are running well I'd clean the mating surfaces, put nice new gaskets on, tighten up the bolts, put deck hatches on and enjoy the boat.

If you think the rust made its way into the valves...by all mean do a compression test. If good, new gasket, tighten up the bolts and enjoy.


While that is what I say...make sure your manifolds are in good shape, hold pressure.
You said new riser...so they should be good to go.

I made light of it...but I would do a compression check just for a piece of mind. With exhaust manifolds off the plugs are right there it is so easy not to do one.

How'd rust get there...well old leaking risers could have been the culprit. 2000 hours they have been changed a few times could have been way before you owned. Could have been a bad manifold from years ago. Also steam after shutdown goes back to the exhaust ports...of can. Rust develops.


Its a boat, do your maintenance, be safe, be vigilant, be preventive ...but don't go fix' n what ain't broke.


...and welcome aboard!

I’ll second what Peter said about long blocks. I’m on my third season I of chasing down all of the shortcuts the previous owner’s mechanic took (“Just keeping the old man’s dream alive.”)

Peter,

What kind of ignition system does Michiganmotorz ship with their complete engines?

Carl - I am hoping you are right!

The exhaust manifolds might actually be original though the riser have been replace at least once by the former owner.

I going try and and a compression test this weekend (need a friend to turn them over while I'm in the hatch).

Any suggest of what to spray into the exhaust port to try and clean then out (rust)

Unfortunately, I don't trust the marina to do the work based on prior experience.
[was given bill recently to discount a hatch to because the didn't know where the switch was, even though they were supposed to do any work before I showed up]

If anyone has a yard shop they do trust in the mid chesapeake I'd like to know.

Peter

I believe it’s a Delco voyager ignition kit

Pete

Personally I'd leave cleaning the rust alone inside the ports, no squirting, scraping, blowing or spraying. Clean the flange faces of motor and manifold where the gasket seals and I'd leave the rest.

I may be wrong, but I think you can do more harm getting rust flakes, dirt and debris down into the ports...

-if the valve is open stuff goes into the cylinder
-if valve is open stuff goes between the valve and seat.
-when the valve opens stuff goes in.
-spray or blow stuff goes up in the...

This can be one of those times you do more harm trying to do the right thing.

When the motor starts...it will blow all that flakey rust in the correct direction...out with the exhaust.



Now I also have not seen what you saw...so there is that.

If you saw water or think water was there recently...like since it was last running. Pull plugs and turn the motor over to make sure no water is in cylinders by cranking or barring motor... BUT again you must pull plugs to avoid hydraulicly locking the motor. Then again you said rust, not water.


You can also hook up a remote start that jumps the solenoid so cranking and watching gage becomes a one-man operation. Or jump solenoid

Carl,

I hear what you are saying but why not pull the heads and do a valve job?

Engines put in in 94, average life span of risers is 5 to 7 years. You are probably on the 3 set of risers.

Tony Meola wrote:Carl,

I hear what you are saying but why not pull the heads and do a valve job?

Engines put in in 94, average life span of risers is 5 to 7 years. You are probably on the 3 set of risers.

Of course that can be done...and with so many hours I'm sure a valve job would add back some performance. But why stop there...

From what I read, maintenance was being done and some rust at the exhaust port....

I did not hear anything about motor not running well, lack of power, bad economy, harsh noises...he just saw some rust at the exhaust port. Could have happened recently or many years ago.

I am a firm believer in If it ain't broken, don't fix it. It's right up there with the enemy of good is better.

Have a problem address it...but don't fix a problem you don't have. Compression test it by all means...but don't go looking for trouble.

I think I beat that dead horse enough.

Now if looking to refresh motors as you think it's time, have the money, the budget, the people to get it done and don't mind sitting out the season till it's done...go for it!

Word of caution

Carl is not a mechanic nor does he play one on TV.
All views expressed in his posts are personal opinions and not necessarily the views of this website.

I'd just add finding a local mechanic that is capable, knowledge, honest has been part of the issue.

[additionally there is limit of what I can do myself as I live in a small condo and dont think the spouse is cool with 2 big blocks inside]

hope to get the compression test done this weekend

hlblake wrote:I'd just add finding a local mechanic that is capable, knowledge, honest has been part of the issue.

[additionally there is limit of what I can do myself as I live in a small condo and dont think the spouse is cool with 2 big blocks inside]

hope to get the compression test done this weekend

Fontg see a problem with big blocks in the living room. Had a crazy neighbor that used to keep his motorcycle in his living room.

hlblake wrote:and dont think the spouse is cool with 2 big blocks inside]

That is understandable.


...do one at a time!

Ha! Don't think that will fly either.

You might need to start watching your back for just floating that idea.

Carl - against my better judgement I passed on your suggestion ...... she did not find it very funny

Per a recommendation from john over at worton creek, I removed the spark plugs and spraying in some Marvel Mystery Oil
(I also sprayed some into the exhaust ports, and noticed a difference after letting it sit).

I then did a compression test, though the results appear to be mixed

With all the plugs removed, I just cranked the engines over using a battery.

The starboard engines numbers weren't that bad:
mostly around mid 140s to 150 compared to high 150 10 years ago during the survey

The port engines results were not as good:
as I had a cylinder a 50, 60, 90 in addition to the others in the 140s (compared to 140s - 150, 10 years ago)

Regarding the port engine I was loosing coolant the last few times I was using the boat

Additionally mechanic who intactly helped me remove the risers and exhaust manifold did try forcing rotating the port engine with a ratchet connected to the crank bolt, prior to soaking with oil (while I believe he was trying to help not sure if that could have cause issues with the valves properly seating where I am reading low compression)

Just wanted to see if anyone has any suggestions? Or is just time to pull the engines and replace/rebuild?

Does anyone know the specs of the 1994 Crusader 7.4 XL with throttle body injection or how to find it? I believe my engine is a Gen V, but there are numerous 7.4 configurations (cams, heads, etc)

I am trying to determine if:
- a Gen VI long block with work with my Gen V intake and throttle body injection (looks like there are some new ones available for high $6,000
- if a go the recondition long block route, I want to make sure I am replacing like for like: prices seem to be all over the price under $3000 - $6000
- have a rebuild done by a higher end machine shop / engine builder, quote is about $6,000

Additionally, are they any changes upgrades anyone would suggest, that would be an improvement? switch to roller cams, 502 or 496?

while some added performance (speed at cruise) would be nice; durability, and reliability are my primary goal

While I do not have flow scans
I was cruising around 24+ kts before with an approx 1 mile per gallon burn rate at 3200 - 3400 rpms showing on the gauges in the dash
(though I know the tachs in the steering console would measured different than if you hooked up a photo tachometer to the engines themselves)

Props should be Nibral, 18 X 21 X 3 blades (i believe there is a slight cup in them as well)
Shafts are 1 3/8 stainless

hlblake wrote: Regarding the port engine I was loosing coolant the last few times I was using the boat

Additionally mechanic who intactly helped me remove the risers and exhaust manifold did try forcing rotating the port engine with a ratchet connected to the crank bolt, prior to soaking with oil (while I believe he was trying to help not sure if that could have cause issues with the valves properly seating where I am reading low compression)

From the original post, I was under the impression the motors where running fine and you were doing routine maintenance coming across some rust in a port.

Losing coolant, having to bar a motor over, and "after soaking with oil" has me thinking this project may have been started as something other than routine maintenance on a good running motor. Or it went south after starting.


I'm not of much help at this point...I know I'd do some checking to try and figure out if valves or rings are leaking to direct me to just pull heads or the motor.

Who I but the boat away for the season 2 years ago, I was noticed on the last few trips that I was loosing coolant on the port engine.

I did not originally plan on it sitting so long but stuff happens

It was suggested that I just spray some oil in just as a preventive measure do to the time they were sitting.

While both motors turn with no issue with I hit the starter compression is low on 3 cylinders on the port side

which brings be back to my original question regarding engine rebuild repower opinions.

also is there a way to test is the gas in the tanks is good or need to be pumped out?

to clarify he had left most of the spark plugs in when he trying to crank it with the racket
they also did some of the stupid stuff before I arrived, even though they were supposed to wait and help me not do stuff themselves

which is why I was looking for recommendations for mechanics and yard that handle repowering

Not sure that turning the engine over with a bar would really do any harm, unless the guy doing it is the Hulk.

You said rusty valves, could be you have bad seating valves which would cause low compression. 2000 hours on the engine, and compression issues. I might feel more comfortable pulling the engine and asking a machine shop to see if it can be rebuilt. Loosing coolant can be several things.

Were you seeing steam out the exhaust when you were running? That would indicate that the coolant is burning off. Could be a bad head gasket, cracked block etc. Have a friend who has crusaders in his boat and was loosing a quart of coolant every time out. Turns out that there is a bolt that runs down thru the water jacket and it was stripped. The coolant was getting out thru that bolt.

Unless you are really mechanically inclined, I would leave this one up to a engine rebuild shop.

I'd say yes I'm pretty mechanically inclined (automotive engineering background) but I don't have a shop/space to do a lot of this work myself, nor every tool that I would need.

Which is way I am looking for a quality yard/mechanic recommendation on the mid Chesapeake Bay (preferably with experience in boat repowering)

While I haven't done a leak down test yet, I think there is a high probability of valves sticking