1991 Civic Overheating

Tiny
BENGA
  • MEMBER
  • 1991 ALL OTHER MAKES ALL OTHER MODELS
I have a 1991 Civic DX 1.5Lwith 250K mileage. It overheats and I had a mechanic look at and he replaced the head gasket and said a cylinder head check showed no cracks. However, the problem didn't go away and I don't trust the mechanic (long story).
The engine builds pressure in the cooling system and forces coolant out to the reservoir which overflows coz I leave it slightly loose so it won't burst to help relieve the pressure build-up. When it overheats, the upper radiator hose is hotter than the lower hose. I've also had this upper hose burst twice. There's also a trace of oil in the coolant but I can't notice any oil degradation from coolant seeping into the oil even though I suspect it's present and I just can't notice it.
Since the pressure comes from the engine, I feel I have 3 possible problems.
1. Improper installation of the head gasket.
2. Cracked cylinder head.
3. Cracked engine block.
Any ideas on which one of these is the problem? If the problem is either the gasket or the head, I'm willing to attempt to fix but if it's the block then it's obviously not a viable fix. Any possible issues to be on the lookout for if I decide to chance replacing the head and gasket?
PLEASE HELP! AM GETTING DESPERATE!
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Saturday, January 27th, 2007 AT 6:57 PM

3 Replies

Tiny
BRUCE HUNT
  • EXPERT
I would question the use of the mechanic and why you ever went to him or back to him. Then I would leave the radiator cap off and run the car until it gets warm. Observe and see if there is any bubbling in the radiator. Just from what you have said about the oil in the radiator leads me to believe the block is the problem. Especially, if the mechanic did ANYTHING right or half way right there should have been atleast some improvement if it was the head gasket.
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Sunday, January 28th, 2007 AT 9:26 AM
Tiny
BENGA
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There was a bit of improvement after the gasket change - just not enough to make a difference. Running the engine with the radiator cap off, I notice bubbles - actually the coolant starts to overflow pretty quickly, long before the engine reaches operating temperatures. And lately, I have also noticed that the engine is burning coolant when the engine is cold, i.E. Coolant being combusted. Actually it's burning coolant all the time, just less when the engine is hot and cruising (not in street traffic - in street traffic it overheats quickly and pushes coolant out the reservoir fast).
So why do you think it's the engine block? Any particular sign that immediately points to this?
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Wednesday, January 31st, 2007 AT 12:49 AM
Tiny
BRUCE HUNT
  • EXPERT
The jacket of the coolant is not all that thick between it and cylinder. There could be a small gouge or grove on the block. The head may be just fine now and the now gasket might slow the flow. But when you mention the trace of oil in the coolant that points to the block. Remember that the oil pressure is a bit more than the coolant. This does not sound good and if the mechanic didn't warn you at the time he should have let you know there could be deeper problems than just a head problem.
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Wednesday, January 31st, 2007 AT 10:35 AM

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