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Hot tank an engine block

S

Stephen Newell

Well-known Member
Looking on opinions on having an engine block hot tanked before an overhaul. The nearest place to be is a half days work just to deliver the block to them. Is there really that much benefit? I've been considering either doing it myself or just remove all the freeze plugs and spray the inside with oven cleaner and power washing.
 
I'd invest the half days work to have the engine hot tanked. Most engine shops that machine blocks for rebuild have hot tanks in-house.
 
I'd say it possibly depends on why the engine is being repaired ? Many of the hot tanks in my area do not clean that well. Some of that might be do to the "good" chemicals not being made anymore. I have done a few rebuilds where I wanted the original condition of the paint on the engine left alone. I got them scrubbed out really good. I even got small brushes to scrub into the drilled passages. These were not sludged up and did not have metal from a major failure running through them however. Mineral sprits in a pump up sprayer and scrub brushes does a good job.
 
This is my first time doing a full engine overhaul so I'm reading a lot and a hot tank was recommended.

The problem with the engine was a blown head gasket. Once I broke it down I discovered both heads had a crack up to the valves so they will be repaired or replaced. It's just the block I'm left with myself. Before I got to this point everyone was recommending replacing the freeze plugs. It seem silly since none of them was leaking but I removed one and found a considerable amount of sludge packed up against the freeze plug. It's the cooling system I'm worried about. The exterior of the block is easy enough to clean.
 
You are getting it bored, right?

With that many miles, and getting it hot, real good chance it needs boring and new pistons, and new cam bearings, crank miked and probably turned, rods checked, etc...

All those things, and the block cleaning, can be done at the machine shop. You'll be there for heads anyway.

Taking shortcuts will bite back! Especially if Murphy can find a reason to pull it back out of that van!
 
Yes I will have it bored. The pistons nearly rattle in the cylinders until the last 3/4" pulling them out of the cylinders.

The crank isn't in bad shape. I had replaced it about several years ago and the main bearings. I think if I just replace the main bearings I will be good. The cam shaft, I haven't gotten it out yet. Will be doing that today.

How do you tell if a piston is bad? They look like they are in really good condition. There is only a slight discoloration on the top. Where it connects to the rods there is no play at all.
a281606.jpg
 
Cracked heads ? what is this in a Chevy ? if it is you can likely buy a reman or NEW crate engine for less than it will cost to rebuilt one.
 
If the pistons rattle, how do you expect to reuse them? And the block is worn except for the last 3/4", it is worn. Heads are cracked.. Replace the engine.
 
It isn't just the water jackets that's important. The oil galleries and drains are right up there too. My machine shop hot tanks the block and heads. Replaces the cam bearings, freeze plugs and bores the block. Resizes the rods and replaces the bushings. Whatever the heads need is done then.
 
(quoted from post at 12:52:06 10/03/18) Looking on opinions on having an engine block hot tanked before an overhaul. The nearest place to be is a half days work just to deliver the block to them. Is there really that much benefit? I've been considering either doing it myself or just remove all the freeze plugs and spray the inside with oven cleaner and power washing.
Click to expand...

Here's the thing: If it's a 350 Chevy, you can get a new one for $1500. So that's your price point. Most shops hot tank a block as part of the boring job. Most hot tanks use a very caustic solution that will ruin the cam bearings. And you're going to need new freeze plugs. (Now's the time to do that) It's common to pay close to $500 just for this part of the process. Add in new pistons and the labor to connect them to the rods (Don't forget to have the rods and block magnafluxed) and it's already getting too expensive to justify the time and effort.

When you're dealing with a less common engine (more valuable), the numbers are easier, but everybody should do the math every time.
 
Considering that this engine has a lot of miles on it, has been overheated, and is about as common as they get, why would you even want to consider a rebuild?
Buy a long block, put your manifolds on it, and call it good. You will save a lot of time and money in the process.
 
Has anybody done the numbers recently? I did a 350 about 2010 and kept track of the numbers. I did the hot-tank, new freeze plugs new bronze valve guides, mains were fine just new bearings, new pistons(not high compression), had new rod bearings and the rods checked. That engine was punched out a full 30 over. Cost was $3000; then I got crazy and did a Eldebrock(sp) point injection system which was $3000 by itself. The engine runs fine and from my experience will last 200,000 miles. I don't know what a crate engine will do BUT I know my work will last will a crate manufacture stand behind their work that long?
 
It has always been my understanding that a crate engine is NEW. As in BRAND NEW, never used. So, are you saying that your work makes an engine better than new?

Keep in mind that we are talking about a really high mileage engine that has been overheated to the point of cracking heads. Once an engine has been that badly overheated, it will probably never be right again. So, why advise the guy to put lipstick on a pig??
 
"how do you tell if a piston is bad",,,need to check the ring lands for wear and check skirt for scuffing and measure, plus rod bore wear. also if your boring the engine you wont be using those pistons! it will be new ones.
 
Good luck finding a shop that is still running the good old fashioned hot tank. EPA regs have virtually forced all of them out of business.

Now-adays it is a big oven and shot or soda blasting, etc.
 
The old fashioned hot dip tanks are probably gone. The dealership I work for has what amounts to a dishwasher on steroids. It's big enough that a bare block will fit in it. The solution I'm told is detergent and microbes. It will completely degrease anything put in there long enough. It's just a pump with nozzles with a heater and a rotating table.
 
Ford diesels like the 3 cylinder in the 555 backhoe, some have porosity issues between the water jacket and oil gallery. We found out the hard way after a hot tanking.
 
If they still have a hot tank, they must be real busy. Call them see if they have a pickup place in your town. The shops in my town got rid of the hot tanks years ago. Now they have spray booths like others have mentioned. I would replace the freeze plugs. especially the one behind the flywheel. If you have access to a pressure washer, and a bottle of degreaser,from any hardware store, or just a garden hose and parts cleaning brush, and a spray nozzle. You will get the motor
clean. Stan
 
New engines do NOT have bronze valve guides and that wears fast with oil running down the guide into the cylinder. And I've seen more then one engine with the cam keeper broken. And the rockers drilled crooked.
YES when you do your own with a GOOD machine shop you get a better job.
 
Sorry didn't read to the end of your reply.
An overheat engine merely take the stress out of the metal. Most drag racers I know want used motors has a starting point.
When I was freshly out of college I had a 1962 Chrysler 300H. Little background; Chrysler took their lightest body off the production line (A Newport) Married a custom built BIG motor (A 300A had a 396/39? hemi with raised compression, special intake manifold--those motors were used for year as the starting point for the drag cars) by 1962 it was a 413ci motor with custom intake manifold the valves were huge and the small motor made just over 400 hp and it really would peg the speedo at 140 mph don't ask how I know. The valve were so large that the metal between the intake and the exhaust was very thin and would crack with just slight overheating. I got very good at changing heads; would figure out which had broken go to a wrecking yard for another head, get it rebuilt then replace the broken one with the newly rebuild one in about 2 hours. I remember one trip I took to Deception Pass--it got to smoking on the way and on the way home some guy thought he would race so I just ran off and disappeared. The rings broke on one piston.
The whole point is that overheating isn't all that bad, It's cracks that are not so good.
High Mileage motor? I had a turbo'ed 4 cylinder motor that broke the rings on 2 cylinders after 100,000 mi. I think the rings broke because of too much pressure from the turbo. I rebuilt the motor doing all the things I've talked about; Bronze valve guides, high quality bearings and rings. I also bored the cylinders and put in sleeves and new pistons. The motor is still running with no lose of power and no burning of oil. It has like 350,000 mi. on it today.
Your not putting lipstick on a pig your building a keeper and depending what else you do maybe a racehorse.
 
If that's the 200,000 mile one you over heated I'd check prices on a remanufactured. Dealer I used to work for sold a lot of GM Good wrench engines.
 
They didn't actually rattle, they were just super easy to slide in the cylinder except the very end. You could tell the cylinders had wear by the feel. I had to take a large dowel rod and a hammer to get the pistons the rest of the way out of the cylinder.

In my area that engine is $1900.00 for a long block. I need to get the cost down as much as possible. I'm going to have to change things like the water pump and power steering pump as well on this project.
 
No mouse nests but three places had two freeze plugs. Someone just pushed the old ones all the way in and drove another in behind it.

There wouldn't be any nests anyway. Up until last week this was my work truck that was used daily.
 

Stephen,

I have both a hot tank and a good wash cabinet ,cabinet does not do as well as
the hot tank and a hot water high pressure washer. Cabinet is quicker and does a
good job if the engine is not terribly dirty. An old engine that is black with
baked on crud will not clean in a cabinet as it cannot blow the solution into the
push rod and lifter area .Did a perkins and a JD4020 this month ,they cleaned well in
the cabinet as they were both diesel ,diesel oil keeps the block cleaner inside.
I am doing an older case 200 engine to build into 300 engine ,ran the block in the
cabinet and push rod area was still terrible. Soaked with 2+2 to cut it , then to
the pressure washer and both flavors of gunk to finish the job. Been building engines
for 40 years and nothing will compare to a hot tank and pressure washer .

george
 
The irony of it is I used to have a caustic soda tank you could easily dip a half dozen motors at the same time. I used to own a furniture refinishing shop and had a dip tank for dipping house doors.

I dropped off the block at my local napa store. They will be doing the cleaning and machine work. Tomorrow I will be looking at junk yards for a couple heads.
 
I personally don?t know prices but I think folks are right about it being cheaper to buy a crate motor. What are you in the paper shredding business?...paper strips all over your tear down area.
 
Time will tell. I think I will save money rebuilding the engine. I found some heads today at a junk yard and now the block and heads are at the machine shop. Right now I don't have any customers calling so I have more time than money. I think by the end of next week I will be all done.

I was mistaken on the engine. It was suppose to be a Chevrolet 305 engine but someone at sometime put a 350 in it.
 
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