Not wanting it to be a head gasket

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

R0cketMan

Member
Joined
Aug 7, 2018
Posts
5
Reaction score
3
Location
Ann Arbor, MI
I had an old 1991 Ford Explorer with a 4.0l v6. It ran well for a while then the temperatures started creeping up. It eventually got so bad, I could drive maybe 10 minutes or so before having to "burp" the coolant system by opening the radiator cap, and quickly, before the temperature pegged the gauge. Other than this extreme condition which caused me to put the vehicle down for service, the vehicle operated a bit warmer, but it was never a problem. The expedition has a surge bottle with a pressure release cap that could be releasing gasses being built up from localized boiling, etc.

Long story short, the shop found BOTH heads were cracked in the exhaust ports of the cylinders closest to the firewall. There was no oil in the coolant or vice versa, and no carbon in the coolant at this time either, just the exhaust gasses creating air pockets in the coolant system. If you suspect ANYTHING wrong and the repair requires the cylinder head to be removed, have the cylinder head "Magna-fluxed", or checked for cracks. Had I not asked the mechanic to do this with my Explorer, I would have paid him for replacing gaskets unnecessarily while the issue remained unfixed.
 
OP
OP
tekrsq

tekrsq

Full Access Members
Joined
Jun 14, 2017
Posts
134
Reaction score
35
Location
Chesterfield, Va
Long story short, the shop found BOTH heads were cracked in the exhaust ports of the cylinders closest to the firewall. There was no oil in the coolant or vice versa, and no carbon in the coolant at this time either, just the exhaust gasses creating air pockets in the coolant system. If you suspect ANYTHING wrong and the repair requires the cylinder head to be removed, have the cylinder head "Magna-fluxed", or checked for cracks. Had I not asked the mechanic to do this with my Explorer, I would have paid him for replacing gaskets unnecessarily while the issue remained unfixed.
Yeah, honestly, I'm learning more towards cracked heads than a cracked head gasket. Anytime a head comes off my vehicles, it gets magna fluxed and x-rayed. It's stupid not to.
 
OP
OP
tekrsq

tekrsq

Full Access Members
Joined
Jun 14, 2017
Posts
134
Reaction score
35
Location
Chesterfield, Va
Try running the truck at load (the point where you see higher temps) with both the front and rear heat set on on high temp and high fan and all windows open. This will essentially expand the size of your radiator. First take note if the both heaters are putting out very hot air, indicating good coolant flow and then if this helps control the engine temp. If you get a lot of hot air and it lowers engine temp, it would indicate not enough enough coolant flow moving through the primary flow circuit. If you don't get very hot air, that would indicate not enough coolant moving through the system at all.

Besides a cooling system pressure test, you can also do a static compression and leak down test to get a better feel for the status of the head gasket, head and block.
Tried playing with the heater this weekend. Heat was normal, and didn't see any changes in engine temp one way or the other.
 
OP
OP
tekrsq

tekrsq

Full Access Members
Joined
Jun 14, 2017
Posts
134
Reaction score
35
Location
Chesterfield, Va
Any update on finding your problem?
Yep, afraid so. It ended up being a cracked head. Because of the design of the truck and engine, I found out that (in my area at least) is was $1,000 MORE in labor cost to replace the head/ head gaskets, than to replace the engine. So after much research, I decide to just put in a reman engine. At the end of the day, it only cost about $750 more than buying an new head and replacing both head gaskets. Truck is in the shop now getting the engine switched out.

Had this been 5 yrs ago, I would have just replaced the head myself, in my garage. However due to back and leg issues, I can't hang over the engine bays or roll around underneath them any more. So I had to have a shop do the work.
 
OP
OP
tekrsq

tekrsq

Full Access Members
Joined
Jun 14, 2017
Posts
134
Reaction score
35
Location
Chesterfield, Va
New engine is in, and almost 500 miles put on it. I initially had an issue with the brand new engine running "warm"....in the area of 210-215F on an 85F day, running at 70-75 mph. After watching my gauges for about a week, I was hoping the issue was a faulty thermostat....even though it was also brand new. So after talking with the shop, I found out they installed a MotoRad 195F "failsafe" thermostat......a $10.00 thermostat in a brand new engine. So, I bought a new, Motorcraft 192F thermostat ($30.00) and installed it. So, for the last week back/forth to work...90-95F days, running 70-75F, my truck has comfortably run about 197-200F. I haven't pulled a trailer yet with it, but it definitely seems a helluva lot better with a "name brand" thermostat in it.

As a side note, I grilled the shop to see if they "cheaped out" on any other parts. It seems they used name brand parts and gaskets on the rest of the sway. It seems the cheap thermostat was an "in stock" item they routinely use. So, I guess time will tell, but the engine runs pretty well. It does have a slight miss at idle, but the shop did inform me during the swap that some of my injectors looked a little "rough" . However, I didn't have the money at the time for brand new Motorcraft injectors. I know, I know, but money is TIGHT right now.
 

Machete

My Rig. 2000 EB 4x4 5.4L
Joined
Jul 18, 2012
Posts
843
Reaction score
348
Location
Illinois
would injector(s) cause a "miss" or is it spark plug/COP issue?
 
OP
OP
tekrsq

tekrsq

Full Access Members
Joined
Jun 14, 2017
Posts
134
Reaction score
35
Location
Chesterfield, Va
would injector(s) cause a "miss" or is it spark plug/COP issue?
Plugs and COP's will cause a misfire, but so will bad injectors. They're electrical devices too, and can fail, not to mention the normal carbon buildup. The plugs and COP's have about 15,000 miles on them. I've ran injector cleaner through it multiple times over the years, but apparently there's still enough buildup that the mechanic things they need to be replaced. Besides, they've got 213,000 miles on them. I'm sure they're tired. lol
 
Top