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-   -   another boost loss thread... (https://www.miataturbo.net/diy-turbo-discussion-14/another-boost-loss-thread-48393/)

chicksdigmiatas 06-18-2010 12:52 PM

Compression test that shiz, and did you check your egr yet? Just stand back and take a breath. Your thinking to hard, check really well for stuff that could have fallen off, then compression test.

Edit: Who knows what temp you had it to, my temp gauge reads the same from 160-195.

Pen2_the_penguin 06-18-2010 01:09 PM

dont worry, I am going to. As soon as I get off from work its straight to my buddy's shop.

fooger03 06-18-2010 02:10 PM

you dont want to simiply disconnect the vaccuum line to the bypass valve, as soon as you do that, it will see vacuum relative to the intake tract and dump your boost.

Two options are to set up high pressure to the BPV vacuum line (get a long vac hose, run it into cabin of the car, attach a hand pump to it, and pump it shut) or take the BPV out of the system altogether. You can also grab the low side of the BPV off where it connects to the turbo low-side, and point it at your face to see if it will dry your hair at WOT.


Originally Posted by Pen2_the_penguin (Post 590374)
I didnt have anything to block it off with, and I couldnt find a piece of piping lying around that would just replace the section of plumbing, but all I could do to at least TRY and block it off, was disconnect the vacuum line and set it to the tightest it could go, and still same problem. It doesnt help that I trusted my car to a piece of shit valuecraft thermostat, now it may be causing a world of hurt. Lesson learned. The car's stock temp guage was reading a little past the hot bold mark, thats how hot, and I noticed it when my speed at 85mph was decreasing, and I freaked when I saw it. If its the whole head or just warped valves, im in luck to have an extra head lying around, and I am kinda glad I didnt sell any of the parts yet.

Oh fuck :barf: , im going to be sick to my stomach...thats not good :( get it compression checked. :fingerscrossed:

Recap: You were driving down the highway at 85mph, and suddenly the car started slowing down dramatically or requiring substantially more throttle pedal. You checked your gauges and your thermometer was pegged full hot.

Is this correct?

If so, I'm afraid you may have problems substantially more significant than a boost leak.

Theres a big difference between "i saw my car overheating" as we previously thought, and "my car lost a lot of power, that's when i noticed it overheating" as we may be learning just now.

Or, maybe you're lucky and the temp sender broke at the same time a part of your BPV malfunctioned?

kww502 06-18-2010 05:13 PM

If you overheated your engine to the point of losing power. You most definitely have some engine problems. You need to definitely perform a compression check and a leakdown test wouldnt hurt either both testers are pretty cheap and great tools to have.

Pen2_the_penguin 06-18-2010 09:59 PM

is it different when the car itself would not let me go over 85 until it cooled down? Even at 5 psi I can accelerate past 85 np. I have not got my compression check yet, but lets assume they were low, where do I check from there? Is it possible to hone and change piston rings if they are at fault while the engine is still in the car? I am hoping its a head or valve issue. I do get the click sound, and I know for sure at least one cylinder is going to be off, since there is less resistance on the engine when turning over the starter.

chicksdigmiatas 06-18-2010 10:07 PM

New long block and profit. 5 or 6 speed swap while your at it.

Pen2_the_penguin 06-18-2010 10:21 PM

does anyone know the cheapest yet decent build configuration? This is my second $500 motor, and I will be super pissed if its past the point of no return. I have a very low budget right now, and it may even have to wait.

fooger03 06-19-2010 10:05 AM


Originally Posted by chicksdigmiatas (Post 590597)
New long block and profit. 5 or 6 speed swap while your at it.

Fixed.

Your block will never be 'right' again. Even if you plane the head-block mating surfaces, you've still got warping in bearings, bolts, parts, seal mating surfaces, etc. etc.

The cheapest build is probably a stock CL motor find, and install as is. Afterwards, be a bit more attentive to the gauges.

kww502 06-20-2010 05:21 PM

Yeah I agree with fooger that motor probably has a few problems and would take a good bit of machine work if its salvagable. A leak down will tell you more.

Pen2_the_penguin 06-20-2010 09:37 PM

good news and bad news. Never did a compression check, but instead took a gamble of which I would not do and got lucky! It turns out I have two stuck valves, same cylinder (#4), and a cracked hydro lifter. Thats the bad news, the good news is that the head isnt warped, needs some machining where the valves got stuck, and obviously a new head gasket, but im going to get to use my head that I never ever got around to sell, and do a port polish. One of the exhaust valves looks a little warped, and I am going to replace the piston rings while im here. Should I invest in some ARP studs and bolts while im here? What else can I do under $200 while im here? Thanks to you all for helping me find out what the hell the problem was, I would never think it was internal until its too late. I got some pics to show so you guys would not just have a pictureless thread, but I have to upload them later.

Pen2_the_penguin 06-23-2010 01:18 PM

lol the head is cracked too, but I never noticed it burning coolant since it has straight water. Just an fyi: if its says "Value" in the brand name, dont bother.

fooger03 06-23-2010 02:26 PM

How do you know the head isn't warped? you eyeball it? :giggle:

99.98% chance your block is still fucked. At the minimum, you'll want to rebuild it, to include new bearings all around and line boring the main bearings.

your stuck valves and cracked lifter aren't the problem - they're the easiest to spot of the symptoms. You're going to feel like a total idiot after you've got this all 'sorted out' and your oil pump shreds itself 50 miles into a 100 mile drive. Would you ever think it's internal until it's too late?

ARP Hardware isn't absolutely necessary. Assuming your stock stuff didnt stretch out under the heat, the only thing ARP stuff is going to do is make it much more convenient to install the head/gasket. It's nice to have, but your $200 is going to be better spent on a junkyard longblock.

Pen2_the_penguin 06-23-2010 03:06 PM

I have a spare long block, that the new head came off of, its still a good idea to just build that one back up I guess, I might just do that. Do you think that the pistons are fine at least? They SEEM fine, since the other engine was swapped originally for a detonated piston, but the block is in great shape. My idea now is just a complete swap over, put the pistons with new rings on the old block, and this way I get my oil port next to the turbo, instead of the lame 96' block.

Pen2_the_penguin 06-23-2010 03:14 PM


Originally Posted by fooger03 (Post 592562)
How do you know the head isn't warped? you eyeball it? :giggle:


lol, kind of, did what my grandfather does, lays the block side of the head on a perfect flat surface, and did a flash light and wobble check. I used a pane of glass mirror.


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