How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Daniel Wilson Your Own Question
Daniel Wilson
Daniel Wilson,
Category: Medium and Heavy Trucks
Satisfied Customers: 4373
Experience:  Owner at DJ Wilson
65405794
Type Your Medium and Heavy Trucks Question Here...
Daniel Wilson is online now
A new question is answered every 9 seconds

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: 11 months ago.
Category: Medium and Heavy Trucks
Expert:  Daniel Wilson replied 11 months 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 11 months 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 11 months 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 11 months 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 11 months 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 11 months ago.

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

Customer: replied 11 months ago.
OK....I will get the info from the shop and get back with you
Expert:  Daniel Wilson replied 11 months ago.

Sounds good Gary

Customer: replied 11 months 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 11 months 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 11 months 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 11 months ago.

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

Customer: replied 11 months 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 11 months 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 11 months 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 11 months ago.
When I took the head back off, the gasket looked fine.
Expert:  Daniel Wilson replied 11 months 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

Related Medium and Heavy Trucks Questions