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Daniel Wilson
Daniel Wilson,
Category: Medium and Heavy Trucks
Satisfied Customers: 4863
Experience:  Owner at DJ Wilson
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I have a 1996 Mack Dump Truck. It has a 400 computerized

Customer Question

I have a 1996 Mack Dump Truck. It has a 400 computerized engine. It was blowing water out the radiator and we discovered it had a cracked head. We replaced the head. Now it still has a very slight bubble in the water and there is steam coming out of the bottom end of the engine through the breather and the oil filler pipe. Can it be the head that we replaced?
Submitted: 1 year ago.
Category: Medium and Heavy Trucks
Expert:  Daniel Wilson replied 1 year ago.

Hi my name is***** will be glad to help. Was the used head sent out to be checked for cracks and milled for straightness? Was the block deck checked with a straight edge? It is either the head head gasket or block deck and in rare cases a cracked block. I recommend sending the head out to be magnafluxed and pressur tested. If it passes then have it milled and check the block deck.what is the complete engine model and serial number?

Customer: replied 1 year ago.
I don't have that information now. Where can I locate this information? If it is the head, would that let steam go into the bottom end of the engine when it gets hot?
Expert:  Daniel Wilson replied 1 year ago.

Who did this engine work? Was this head bought and just bolted on without checking it or machining it? If so then none of the surfaces could be posibly in specs and would cause a head gasket failure. Was the head torqued to the specs in the manual? Incorrect torque could also cause this

Customer: replied 1 year ago.
A friend that has a shop do the work. The head was bought used, and visually inspected, but not machine tested. Yes, it was torqued by the book in correct sequence. Could this still be the reason the steam is coming from the bottom end of the motor. We are planning on taking the head back off, but just wanted to get advice if this could be the problem, or do I need to look deeper. Can you tell me where to locate the numbers you asked for?
Expert:  Daniel Wilson replied 1 year ago.

the engine info will be on the valve cover tag and the side of the block. Yes this could cause your problem

Expert:  Daniel Wilson replied 1 year ago.

Any used head should be sent out and checked unless it is a reman

Customer: replied 1 year ago.
OK....I will get the info from the shop and get back with you
Expert:  Daniel Wilson replied 1 year ago.

Sounds good Gary

Customer: replied 1 year ago.
The engine model # ***** ***** The serial # ***** ***** My head has a cast # ***** 5335M. The Mack place says that 5335AM and 4468M are interchangeable with my head. My question is that I know someone who has 5341M. Will it not work, and do you know why if it won't work?
Expert:  Daniel Wilson replied 1 year ago.

Hi Gary, Thanks for the info. I recommend sticking to the interchange you got from mack as I can not answer without further research what the differences are. I will see what I can come up with for you

Customer: replied 1 year ago.
What would be the difference between E-7 400 and E-7 427? I am pretty sure it came off of a 427.
Expert:  Daniel Wilson replied 1 year ago.

I would have to check into this further for you on Monday if that works for you?

Customer: replied 1 year ago.
That will be fine, I am going to take the head to be checked on Monday. I took the belt off the fan and the alternator, and took the top radiator hose off, and cranked it up and it is just a very few bubbles coming up every few seconds. But the steam going to the bottom I just don't understand.
Expert:  Daniel Wilson replied 1 year ago.

Can you still do a pressure test or is it too far disassembled already? You could pressurize the system and with the intake and exhaust manifold removed look for white ash deposits ans coolant leaking in the ports.

Customer: replied 1 year ago.
I did do that, but didn't see any. The only thing I did see when I pressurized it was a bubble every 3 to 5 seconds.
Customer: replied 1 year ago.
When I took the head back off, the gasket looked fine.
Expert:  Daniel Wilson replied 1 year ago.

Thanks for the update Gary, Send the head out to be pressure tested and magnafluxed. This is inexpensive and will confirm any problems with your head. If it passes have it milled to spec and then we need to look at the engine block for problems

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