My experience with chasing temp to high
Thought I'd share a recent adventure with my 280GE and it's very germane to all, not just G-wagen owners.
Chasing a temperature gauge registering higher than I am comfortable with.
Symptoms: at idle temp slowly rises towards the right 3/4 mark. At highway speed, okay in the middle to 1/8 right. Confirmed with digital temp gauge. Been chasing it for awhile.
Cooling system condition. When I purchased the vehicle many years ago I knew that it needed a radiator and hoses. So all new plus new pump, deoil, decalicify, etc. Yes I can be picky, especially when I want to baseline a vehicle. Fan clutch checks 100%. All was well for a couple of years.
I don't like replacing stuff in a hunt so I've been patiently running various troubleshooting methods.
Last week I was working under the hood and caught a wiff of exhaust. Not a good thing. Looked and looked and couldn't find anything. So step one for me is to hook up my trusty shop vac at the tailpipe, and pump high volume low pressure air into the exhaust system. Made up a bottle of soapy water and went hunting. Didn't see any bubbles at first but when the solution ran under the exhaust manifold for the forward three ports BUBBLES!!!. I put my hand underneath and a very large volume of air was pouring out. Looked at it with a mirror and this was not a small crack.
Pulled the forward exhaust manifold and wow, there was a huge crack that had been previously repaired via welding. Frankly, I've never seen a weld job, even one done by the pros, hold forever on a manifold. I did notice that the manifold took a tug to get off. I found that the 6th bolt back was stretching port three back, which is probably how the crack manifested itself. Cast iron doesn't like stress. So that hole got reamed a bit to allow proper fitment.
I use POR-15 products a lot and decided to try their Fireseal 2000 manifold repair. A new manifold is $250-$350. (If anyone has one used for a 86 280 GE let's talk). I followed the instructions to the letter. So far so good. We'll see how long it lasts. Anyone ever use this stuff?
But the bottom line is, no more overheat. All of that very hot exhaust gas was pouring/pumping out and hitting the side of the block and then hitting the top right of the block where the temp sender is. And to make matter worse, the fresh air intake for the motor was most likely picking up some extra heated air.
Longest term problem I've ever chased.
I can't believe I went this long without getting carbon monoxide headaches. Says something for the cockpit sealing. Pretty tight. Scary though. Carbon monoxide is bad juju.
S, J.R. Brown
2000 G500 LWB Obsedian Black
2005 Toyota Tacoma Access Cab Off Road Sport
1993 Volvo 240 Sedan Anthracite
1980 450SEL Champange (owned it for 15 years. Great car)
1986 280GE LWB Anthracite (Sold it and kinda wish I hadn't)