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Isuzu 4000: Isuzu 4HF1 keeps on blowing cylinder head gasket,

Resolved Question:

Isuzu 4HF1 keeps on blowing cylinder head gasket, do you recommend replacing cylinder head bolts? Head has been skimmed
Submitted: 5 years ago.
Category: Car
Expert:  Dad Mechanic replied 5 years ago.

JACUSTOMER-j74d4cev- :

Sorry for your trouble. Let me ask you a few questions. Does the gasket blow in the same location all the time? Do you have a steel streight edge? Jim


Gasket does not blow immediately, initially it builds up air bubbles in the radiator. Makes short trips without any problems but on a longer trip the truck starts to overheat and then blows the gasket. The vehicle is then sent back to the repair shop where the engine was overhauled, when they again replace the gasket. We are not able to say exactly where the gasket blows as this is handled by the repair shop. We were informed by the mechanic that the the head bolts could be the cause of the problem and would need to be replaced as they have been overstressed. Would you agree with this? The head has been skimmed and an oversize gasket plate fitted, the head has also been tested for cracks.


Please note that we are still waiting for a reply, we are unable to accept the answer as yet, but may have clicked on the Accept button in error

Dad Mechanic, Mechanic
Category: Car
Satisfied Customers: 202
Experience: I have worked on everyting from Model Ts to 2012 Autos,
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Expert:  Greg replied 5 years ago.

Name is XXXXX XXXXX i will assist you the best i can, please Only accept if you are happy with my answer.


My fellow expert can't assist you at the moment so i will assist you with this issue .


If after the repair and you are still getting a build up of air bubbles in the radiator

then you have a problem with the head , head gasket or a cracked block .


Mating surface of block to head distortion, top of block will have to be checked for distortion , this i have seen many time where the head gets skimmed but the top of the cylinder block is forgotten and not checked correctly.


Head bolts are a big possibility these should be replaced .



Have the shop check the block ,replace the head bolts .


Need further assistance with this issue please let me know.


Regards Greg