The elusive 224/3.7 MerCruiser banger

Beck,
As you are making short runs and not running antifreeze there is less time for leaking and without antifreeze the seriousness of the leak is less but corrosion is more of a problem. Check the oil for water emulsion between runs and you may get by with what you have.

My engines run antifreeze and operate for long periods so any leak is a big problem.

 

Dennis,
You are scaring me a bit. After following this thread for quite a while, I have made a deal to buy two of these motors. My plan is to run one stock with the only major change being an aluminum head. The other would get a rebuild with the deck closed up like Boss9 did earlier.
I would sure like it if I didn't have to do a major rework to the first one before using it.

I suppose that I could live with the iron head while I build the second engine. But, that only prolongs the head gasket dilemma.
Please keep us informed as to your findings on head gaskets.

Thanx,

Bruce

 

Bruce , a closed deck will solve the headgasket problems. boss 9 said his was welded in but I think it was brazed[or soldered] instead as he said it caused no heat warping. I see no need for welding unless the cylinders move around enough to pop loose the added pieces. The aluminum head is good also although I've always run Iron heads as I already had them. When you do the engines it is to your advantage to be able to swap parts between them as one may end up as a parts supply. Always bore a minimum amount as the guys in machine shops habitually start at 30th over but these engines have a limited amount metal there so remove the least possible.

 

At the moment, I am considering several sealants to be used to replace the sealant bead on a fiber gasket
The sealant must:
1. be SOFT enough cold to allow proper compression of it when the head bolts are torqued. (In other words it must be a liquid during assembly)
2. have LOW shear strength than the fiber gasket so it does not tear the gasket apart as the engine expands and contracts in heating cycles. (remains a liquid)
3. RESIST gasoline, water, and antifreezes.
4. Not react with or degrade any gasket surface coating on the gasket.

some possible choices of unknown suitability:
Hylomar {not very strong}
locktite 518 thick liquid, anaerobic, non drying
non hardening "permatex" [the black one]
hi tack a thick purple liquid brush on, air dries

aluminum crankcase assembly sealants:
Kuril very sticky, must cure just before assemly, tan, odd triangular bottle
Hondabond 4 thicker, non drying silicone based 3 oz tube abt $10
Yamabond 4 thin and runny,silicone based non drying 3 oz tube abt $11
three bond1184 thin and runny, silicone based non drying 100 grams abt $17

these need to be applied in a thin even layer silk screening is used by the gasket factory to do that..
not recommended: silver paint

 

I heard from Randy, he likes the idea of adding aluminum to increase the width of the edge of the block between the water jacket and lifter gallery and suggested bolting aluminum there with an adhesive between the two.
Other suggestions from him are trying a long rubber band or 2 feet of o ring material there as a sealing gasket supplement. He has not tried Hylomar there on Mercruiser engines but did use later it on Cometic gaskets for a Northstar engine

 

I got the first of my engines. It was complete with out drive and hydraulics. Took me the best part of 2 days to remove the marine stuff. Now I remember why I hate boats. Hopefully, I can sell that stuff off and recoup most or all of the cost. Free engines are good!

This is going on a stand to check dimensions for a '27 T. I can fire it on the stand. I wasn't planning on rebuilding it before use. But, I need to drill the rear of the crank for a pilot bushing. Anyway, this is a loooong term project, so that is a bridge to cross later.

Dennis,
Thanx for chasing down the head gasket possibilities. Adding a chunk of aluminum seems like a great fix. I haven't looked at the problem area yet.

 

Here are some of the better instruction videos on aluminum soldering/brazing (the difference is in the temperature involved 740 F is the dividing line


this man does it right and explains it well

 

I've only been able to load one video per post so here is another showing good points:

as the filler rod does not penetrate the aluminum you have to be sure that all of the aluminum is hot enough for the rod to stick to it. He drags a little screwdriver in the puddle to aid adhesion.

 

and another note that the instructions apply only to the rods of this company.
https://www.youtube.com/watch?feature=share&v=Zu-VZ5K79pY&app=desktop

One of the rods melts at 350 F. that material is like one I used 50 years ago I was impressed with how easy the solder I used was to work with. The lower the melting temp is, the more tin is in the solder. Zinc is mixed in for stiffer solders that melt at much higher temps. Tin makes a noise (called crying) when it bends I had a3/4" tin rod that I kept just to amuse myself with its odd sound as I bent it easily in my hands . The softness of tin may limit its use. Some of the aluminum solders are quite stiff.

 

1. None of the above is welding. In gas welding aluminum, the best filler is the exact same metal type you are welding. It is easier on some alloys than others.

2. An old technique to gauge the temperature of aluminum is to smoke it in an acetylene flame, the smoke burns off at 700F. This temperature is enough to anneal aluminum.

3. Temperature control is critical to getting the metal joined. Heat bleeds off rapidly into other metal touching the aluminum and of course into the rest of the engine block so it may help to preheat the entire block. I have a junk block to try different methods on.

4. Small pieces of metal heat up far faster than large ones. There are other videos showing this problem when the solder sticks to the little hot piece but not to the large cooler one which was not brought up to temperature. They must both be hot.

 

Bruce, the heat exchangers , exhaust manifolds, voltage regulators, alternator stators and rotors can be sold. 4 inch heat exchangers are in demand I get my engines cheap so I give any left over parts to the shop selling me the engines.
He keeps the outdrive so it is probably easy to sell.

If your engine runs, you may want to just try it without removing the head and avoid the gasket problem. But if coolant is in the oil there is a gasket problem.

The head will have to come off to have the back end of the block milled 5/8" shorter to fit a small block chevy bellhousing and manual transmission. I could not get the ford pressure plate etc. inside the chevy car bellhousing but it went into the larger pickup bellhousing easily. As the pickup's transmission aluminum nose is wider, you need to get one to replace the narrow car equivalent and everything will fit.
Everything is different if you use an automatic transmission so I can't tell you anything about that setup.

 

Dennis,
According to the seller, this engine ran about 7 months ago. He purchased it to replace a different engine in his boat. For whatever reason he decided to sell this one and find a direct replacement. I got the engine, outdrive and hydraulic (trim?) unit. It was all assembled with the boat's transom cut around it.
I have a boat mechanic friend that can help me identify and hopefully sell those units and the other marine parts. I have the exhaust manifold, heat exchanger, regulator and stator. The rotor has had all the magnets removed.
Early in this thread, Phil 1934 posted his solution to the block length situation. He made a pilot bushing adaptor the located off the flywheel. He also made a flywheel that was thicker to bring the clutch surface back to adapt the Chevrolet bell housing. I have the equipment and ability to do both, but I will try to avoid making a flywheel. In the far reaches of my mind, I think I remember there being a longer throw out bearing. Certainly worth the effort to research that, as it avoids dismantling the engine to cut the back of the block, and drilling the crankshaft.
I have quite a collection of Chevrolet bell housings, including several different aluminum ones and a Lakewood scatter shield.

Thanx for your continued input on this thread.

Bruce

 

On my adaption from the motor to a T-5 transmission I used a Lakewood housing as being steel it was easier to adapt(modify) to match the engine : I relocated one tab on the passenger side (& the starter "bump" as well) to match the location on the motor . As I'm using this in a Model A with unsplit :bones it provided a place to weld the pivot for the bones, as well as a place to weld my "float-a-motor" style rear motor mounts. Being steel it was a lot easier to modify than cast iron or aluminum.

 

What is the length of your bell housing?

 

https://www.sterndrives.com/470information/470coolantleakrepair.html
It is a good and detailed description of how to work on a Mercruiser engine that is not from the shop manual.

 

It was a standard Lakewood steel housing, but I don't don't remember the length(Depth?), but I did add a 3/8" plate at the transmission "face' to shim the Transmission out. I also modified the bellhousing to incorporate the Model "A" pedals/linkage/etc. into it so as to be functional like the original "A" , at least on first appearance. When I get the project running/driving I plan to put a "build" thread up on this site showing everything I've done.

 

the uncompressed head gasket sealant bead height measures 1.5 thousandths thick it is on both the upper and lower surfaces of the gasket or a total of 3 thousandths. it is a fragile grey material. I measured it where the gasket had not been compressed.
Today I traced the block's water passages and compared the gasket to what I traced. The only place added aluminum will help is within the water jacket as the gasket does not extend beyond the difficult-to-seal block edge into the lifter gallery(as one would expect).
I also checked heat gradients in gas engines and saw the figure of 154 degrees F change per milimeter on the hot side of cast iron* at the combustion to 44 degrees F per mm on the cold side of metal there.
*(I must check the metal type again) as it probably makes a difference in the heat gradient). This is to see which solder will stand the heat of a running engine.

 

bigchief is weighing in on this, he:
1. suggests a video comparing several aluminum brazing rods

2. questions if Hylomar is capable of sealing our application
3. is checking on gaskets and will report back

 

I went to a local metal fab shop and found roughly what it would cost for a plate cut to fit into our blocks to close the deck:
1. I had a jpeg,pdf and tiff files made at a blueprint shop for $10
I used an online file converter and will send the results to the cutting shop.
2.cost estimate for 6.1875" x 22" aluminum 1/4 "thick .. $15
3. shop charge for loading & deburing ...............................$26
4. cutting fee $3 per minute ..................................................$18 to $24 estd
approximately $69 ttl
he began with an estimate of $280 but I'm cutting it way down.

 

Dennis,
I like the idea of closing the deck. With the low temperature brazing, not much chance of distorting the block. One question though, how would you get the block to 700 degrees or so to melt the rod? Do you think an oxy-acetylene torch with a large rose bud tip can keep up with the heat dissipation of a cold block? That's a pretty big heat sink. I'm not sure my oven can fit a bare block, will measure tomorrow. Could preheat to 550 then cover and just expose the work area.
I would be willing to share the cost with you. Maybe some of the other guys would want one or more too. Don't know if it would be more cost effective to have several made and you send them out, or just pay to have the cad file sent to those that would like to have one or more made locally.

Bruce

 

You raise good points Bruce,
Preheating the block will greatly reduce heat distorsion stress in the block and will allow the use of higher temperature rods. Several different soldering alloys of rods are available which melt at a number of temperatures between 350F and 750F.

Rod hardness is more important to me than melt temperature as I would prefer a filler metal that approximates the hardness of aluminum because I have been surfacing blocks with a large flat slab of countertop with sandpaper glued on. This abrasion method requires that the block be of even hardness. (The harder cylinder sleeves have not been a problem, possibly as they are thin)

If the block is sent out to be surfaced by a machinist, braze hardness will not matter as the cutting tool will leave it nice and flat.

In any case, pre heating is worth doing.

The Merc block may fit into a double size oven but if it does not :

1. An old salvage store wall oven could be cut in half and expanded.

2. A chest type freezer could become an oven if heating elements are added.
Its flamable seals would have to be removed but you can braze with it still in the converted freezer

3. Or a metal box with fiberglass insulation batts and an oven heating element could be made.

4. Exact temperature control is not needed so an on and off switch would be adequate. Brazing could be done with the block still in the "oven"
I appreciate your offer, I will provide DWG and DXF files at no cost.
dennis

 

Perhaps ten quartz lights could heat the block gently over a number of hours.
The last thing we want is strong localized heat like a rosebud would provide.

 

Bruce, check what input files your laser cutting shops need. I went to the suggested sign shop to hear that their scanner is too small for something headgasket size. It is just as well because he wanted $85 to convert a jpeg file to dwg file, I looked it up find that it takes only seconds and the converter is free on a trial basis.
Seems a good place to avoid He suggested a blueprint shop that I have used so I will talk to them tomorrow.
dennis

 

Dennis,
I'll have to look around for local shops. Do you think we should compare water jet to laser?

 

Dennis G, I would be interested in one or two of these plates if you have them made.

 

Great idea. Yes, absolutely , I forgot to consider it.

I talked with Jeremy at the blueprint shop who said it would cost less to plasma cut them directly from a jpeg file.
there would be more cleanup with that. The blueprint shop can scan my drawing cheaply but it would be a JPEG, PDF, BITMAP or TIF (raster files) that has to be converted to a vector file a DWG file(open format) or a DXF file (closed format). They send the files out for conversion and some hand work may be involved to touch up the image.


glossary:
Raster files appear "pixilated" when enlarged.
Vector files remain smooth lines when enlarged.
DWG files can be modified by anyone if that is needed.
DXF files are for proprietary information and would not be what we need

 

ok

 

absolutely,

then I looked up the following :
https://www.esabna.com/us/en/education/blog/what-is-the-best-value-plasma-laser-or-waterjet.cfm

after reading this, it seems that water jet cutting is a little better but costs 5 or 6 times as much as laser cutting.

 

I traced the top of one of my blocks had it scanned to a JPEG, PDF and TIIF see jpeg and pdf below

 

a free online conversion changes the jpeg file to a DWG file. :

https://anyconv.com/jpg-to-dwg-converter/ you save that file and take it to your laser cutter guy.

or try this one: in spite of the files being in dxf this converter is worth trying as it claims to be open (what we need) and it has the feel of working.

https://convertio.co/jpg-dxf/