I know this has been gone over time and time again, but I'd like second (third,fourth,fifth..) opinions. A few weeks ago noticed the motor run hot (almost all the way to the red, when its normally at 4 o'clock everytime i glance). Coolant was low, filled it back up and it ran fine, seemingly no coolant loss when i checked it every few days. Fast forward to this week, I've replaced the cap. (which seemed to fix the problem for a few days) Oil looks fine, no milky slime. Fan clutch is perfect. Pressure test on the radiator showed no loss after about 20 mins (maybe i should of tested it longer?) Then back to still losing coolant, with no visible leaks. Then I find it, its being pushed out of the overflow tank. Hydrocarbon test was a mid-way result. Didn't totally stay blue but didn't change to yellow. (thats what bothers me..) Replaced thermostat (stant superstat, what was in it and what i replaced it with), drove it and temp gauge got to about half-way, thermostat opened (apparently) and it dropped back to 4 oclock. no coolant loss. Thought the problem was fixed again (first bad cap, now stuck thermostat) Tonight on the way home i see it overheats to about a third of the way, but doesn't move from there. Limp it home and I notice yet again coolant being pushed out of the overflow tank. I've been thinking the thermostat hasn't been opening, and replacing it and it running fine made me think i was right until tonight. Now i'm wondering if the new thermostat is stuck closed, or it is a bhg indicated by the hydrocarbon test. From here all i know to do is test the thermostat to make sure its opening at the right time, and compression or leak down test. I've also taken into consideration it could be bhg and its only happening when i push it hard, thus it only overheating at times and the contaminated coolant (how else could it get contaminated?) Thoughts?
Possible BHG?
- Thread starter laconic
- Start date
Do a compression test or if you have the tools (or are just getting it done by someone else anyways), a leakdown test. Is there any funny residue inside your coolant resevoir? Any rainbow swirls sitting on top of the coolant in the resevoir and/or the rad when it's cool? Does the exhaust smell "sweet"?
Based on my experience its bhg since your coolant is overflowing. Did you retorque your heads recently? One last question is your radiator the original one from the factory? The radiator might be shot.
^something may be clogged somehow causing the overheating. Though i would do compression check first anyway.
A quick reply to everyone at once..
No residue in the coolant overflow, no strange colors, no "sweet" smelling exhaust. oil looks fine thankfully. radiator itself is pretty new, it was just replaced not too long ago when i got it. i am doing it myself and i have pretty much everything available to me .. (i work in parts, fathers a mechanic, work will be done by myself and other friends who are mechanics)
at this point i still haven't done a compression and leak down test yet, but i think i'm living in denial and going through every possible thing before it narrow it down. i'll update once i do the testing and find out.
No residue in the coolant overflow, no strange colors, no "sweet" smelling exhaust. oil looks fine thankfully. radiator itself is pretty new, it was just replaced not too long ago when i got it. i am doing it myself and i have pretty much everything available to me .. (i work in parts, fathers a mechanic, work will be done by myself and other friends who are mechanics)
at this point i still haven't done a compression and leak down test yet, but i think i'm living in denial and going through every possible thing before it narrow it down. i'll update once i do the testing and find out.
sogi99;1365980 said:
We only have one head.
What about smoke...any white smoke? Are you stock...running high boost...fully built...any recent work done...?
I'd pull the spark plugs one at a time and inspect them....if coolant is making it's way into a cylinder "even just a little" it will steam clean everything...the plug in the cylinder that's got a bhg will look much nicer than the rest...so if one plug has almost no carbon buildup than odds are it's bhg.
Compression test is in order but looking at sparkplugs is a quick inspection.
Compression test is in order but looking at sparkplugs is a quick inspection.
I am still curious as to the story behind this.
Is your car stock...running high boost...how many miles...? Details man...details...
Is your car stock...running high boost...how many miles...? Details man...details...
Sorry, sorry! I guess I haven't provided any back story on my Supra. Its a 88 Targa turbo with TEMS, stock c26, Greddy bov, Tanabe springs, Tokico Illumina shocks, Tanabe 3 inch downpipe, Apexi N1 exhaust, Greddy Electronic boost control and Turbo timer. I run 8 psi boost. It came with all of those mods when I got it at 149k miles and its currently at around 152k. Only real changes I've made (that weren't repairs) was from a HKS filter (which looked horrible, no telling how long it'd be on there) to a AEM one. Stock hg was on it, so it was about time at 152k. Heads already off, and will be going to the machine shop soon. I was thinking of making a thread of it, but since i'm poor like every other mkIII owner, its just going to be fixing everything and getting it back together right. no real upgrading so.. it would be vastly uninteresting.
Thanks for the background info! Upgrades are nice when we can afford them. Otherwise, just keeping an MKIII running will keep us smiling!
If you can spring for them, a set of ARP's will do you well.
Good luck with your repair!
If you can spring for them, a set of ARP's will do you well.
Good luck with your repair!