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At 196k, you're overdue for a valve job anyway. But in the meantime, have you checked the reservoir cap to make sure it holds pressure and have you pressure tested the system? If you have an external leak, a pressure test will show it quickly. Any place that coolant comes out, air gets in...
I replaced the cap a while back. I have often pressure tested the system, but not lately. Hardly a week or 2 goes by that I don't have to open the cooling system for one thing or another, so there are plenty of opportunities for air to get in, and it's next to impossible to keep track of the coolant level. I have noticed some white antifreeze residue collecting at the edge of some of the rubber hoses so I probably do need to do another test and tighten everything up.
I replaced the cap a while back. I have often pressure tested the system, but not lately. Hardly a week or 2 goes by that I don't have to open the cooling system for one thing or another, so there are plenty of opportunities for air to get in, and it's next to impossible to keep track of the coolant level. I have noticed some white antifreeze residue collecting at the edge of some of the rubber hoses so I probably do need to do another test and tighten everything up.
Ah, well if you are opening the system and letting the air in yourself, that's a different issue. I had the impression you were finding air in the system after multiple attempts to vent. Either way, if you are seeing antifreeze residue, then definitely time to test with pressure.
Ah, well if you are opening the system and letting the air in yourself, that's a different issue. I had the impression you were finding air in the system after multiple attempts to vent. Either way, if you are seeing antifreeze residue, then definitely time to test with pressure.
No your impression was right - I do find air is either getting in, or it moves around in there. Typical scenario: I try to bleed the system, seem to get it reasonably ok (heater works etc.). Then within a few days the heater becomes inconsistent again. It will get to the point where I get more heat at higher rpms, and sometimes even hear water rushing/bubbling in the heater core area. Sometimes I'll be able to bleed more air out, other times nothing will come out of the bleeder valve. So I assume maybe there was air that has become dislodged, and I'll just have to keep bleeding it frequently until it's all gone...but before long, I have to do something that requires opening in the system again anyway so I'm back to square 1!
Perhaps V2 rocket can comment on this..If an EGT gauge probes were placed in the exhaust manifold runners, would it be sensitive enough to detect the differences between cylinders in this case? Divil has already tested this with a laser thermometer on the runners and hasn't noticed any appreciable differences..jus wondering..Tiger 03447
Perhaps V2 rocket can comment on this..If an EGT gauge probes were placed in the exhaust manifold runners, would it be sensitive enough to detect the differences between cylinders in this case? Divil has already tested this with a laser thermometer on the runners and hasn't noticed any appreciable differences..jus wondering..Tiger 03447
That's not quite true...I did notice huge differences in exhaust runner temps, but I just can't seem to make any sense of them. The infrared thermometer seems to be very sensitive to distance, angle etc...either that or the actual temps are fluctuating very quickly. It's impossible to hit all 4 at the same location due to the stuff that's in the way. I can hit the flanges at the head, or the heat shields a few inches away (coolant pipe gets in the way). But going through them from 1-4 multiple times, I see different temps on any given runner. Once I saw that 2 and 3 were around 500F, while 1 and 4 were around 350. But after a a few passes I was seeing high 400s on #4, and as low as 250 on #1. I'm not sure this is a valid test of anything...if it is, I need a lot more practice to find anything consistent.
As requested, here are all the plugs lined up together.
Unfortunately, they are making me look like silly now because they are WAY different from when I took the first set of pics. After a little driving #2 has darkened, while #4 has cleaned up quite a bit, with the result that 2, 3 and 4 all look pretty much the same now. #1 still looks a lot darker than the others but the difference overall looks much less dramatic.
I promise though, 2 was squeaky clean when I took those other pics!
I also noticed that the white/grey stuff on piston #2 is still there, looking identical to yesterday (before I drove) so I don't see how it can possibly be antifreeze residue...maybe ash from burned oil?
(Cylinders 1-4, left to right):
I also pressure tested the cooling system - at first I did hear a little noise from the electric pump but it soon stopped and the system held pressure at about 9psi. I wasn't sure how high I should test it but it got pretty hard to pump at 9 and I didn't want to overdo it.
03-30-2015, 10:47 AM
