My 2004 RAV 4 cylinder 110k overheats, sometimes won’t start. One mechanic said a cylinder head might need to be replaced. (He doesn’t do that work). Is there way to tell if resurfacing is the fix or replacement?
Any “mechanic” that doesn’t do that kind of work is probably not a reliable source of information. If you go to a real repair shop, they will do a compression test along with some other diagnostics IF their initial diagnosis points toward a head sealing issue. There can be several causes for overheating. A proper diagnosis will reveal what is required to fix that problem. In the meantime, if it starts getting anywhere near overheating, do not continue to drive. You can do serious damage and increase costs to fix it significantly if you do that.
If the head gasket is leaking, the only way to tell is to remove the head and check both the engine deck and head surface for flatness. If the head is warped from overheating, then it would have to be completely disassembled to be machined flat and then you might as well refresh everything. On a 2004, a used head may be more economical solution but your mechanic should be able to advise the best route to take. Maybe it just needs a new gasket. Maybe the coolant leak is elsewhere…
4 Likes
How did he arrive at the bad cylinder head diagnosis? If there is a problem in the combustion chamber there should be a drop in compression. The mechanic can test for this by pressurizing each cylinder and seeing what air pressure it maxes out at. Leave the pressure gauge on and see if the air leaks down. If there are no leaks then what’s wrong with the cylinder head? If the pressure in any cylinder is low then the mechanic can insert a borescope and inspect the cylinder walls and piston visually. Probably can’t inspect the valves with the borescope. To look at the valves he might have to remove the head unless he can see problems with the valve train after removing the valve cover.
Remove the radiator cap when the engine is cold.
Start the engine and watch the coolant in the radiator. If bubbles start to form in the coolant it usually means there’s a head gasket leak,
Once the head is removed, it can be determined what’s causing the leak.
Tester
Hey Tester, thanks for taking time out ur day to answer my question. I really appreciate the tip.
I found this that could be the problem.
TSB 01507, NHTSA #10021542, Dated April 6 2007.
Coolant Loss on 2002-2006 Toyota 2.4L, 2AZFE engines
The following information concerns the loss of coolant on some 2002-2006 Toyota 2.4L, 2AZFE engines. The location of this condition has been noted at the rear of the engine where the cylinder head bolts to the cylinder block.
It has been reported that stripped head bolt threads have been found on some of these engines during tear down. When the two rear head bolts lose their clamping ability they allow coolant to seep out at the rear of the cylinder head.
To repair this condition, engine builders report using thread repair tooling used for various GM engines. Specifically, Cadillac 4.6L engines use the same threaded head bolts (Figure 1). The head bolts for this Toyota engine may be reused if they are not damaged and meet the following length specification.
Using a vernier caliper, measure the length of the head bolts from the seat to the end.
Specified bolt length: 6.350˝ to 6.465˝ (161.3 mm to 164.2 mm). If the length is greater than the maximum, replace the bolt.
OP, are you having to top off the coolant to keep it at the “full” mark?