Blown headgasket? I have no clue. Help. - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


Engine Performance This section is for discussion on all engine building related questions.
Sponsored by:
Sponsored by:

Reply
 
 
 
LinkBack Thread Tools Search this Thread
Old 05-09-2011, 09:41 PM   #1
Junior Member
Thread Starter
iTrader: (5)
 
Join Date: May 2010
Location: Wisconsin
Posts: 384
Total Cats: 1
Default Blown headgasket? I have no clue. Help.

Warning: Long post (but at least I'll use good grammar, punctuation, as well as paragraphs)

This problem started about a month ago but I haven't had the time to tackle the project. I finish my second semester of college this Friday so I want some guidance as I go back home and start working on the car again.

First of all, here's the specs:
1996 Turbo Miata ~131,000 miles
Garrett GT2554R @ 10psi
Stock motor, cooling system, and radiator
305 injectors, BEGI FPR, AEM FI/C

Like I said, about a month ago I came home from school and started tinkering with the car. I rewired the boost gauge, AEM UEGO gauge, stereo, and even took out an old non-working alarm system. After that I started up the Miata and noticed that it idled very funny as if it were on 3 of the 4 cylinders. My first suspicion was that it was the plug wires or something I did with the wiring. Checked the wires and they were fine. I pulled all the plug wires off one at a time to see which one would not change the way the motor ran. Turns out that when I pulled the plug wire for the 1st cylinder, there was no change in the way it would run, so this narrowed it down to a misfiring 1st cylinder. I drove her around the block and it seemed like there was a decrease in power as well. I let her sit overnight and came back in the morning to find that she ran smoothly, I thought my problems were gone.

The next weekend I came back and my problem had returned! So I checked all the plugs and they looked pretty old so I got a new set and threw them in. Still ran like crap. Went and rented a compression tester and got 120 on #1, 90 on #2, 85 on #3, and 87 on #4. Didn't make much sense to me because those are some pretty crappy numbers, the car didn't run that bad... it was still drivable. For the record, I didn't unplug the injectors or open the throttle for the test so I didn't know if the numbers were accurate. Fed up, I threw the car on jack stands and went back to school for the week.

The next weekend I came home and started the car and the problem was gone... again. It idled nice and I thought things fixed themselves. So I took her on a run and noticed smoke coming out of the tailpipe once I got on the gas. Seemed about as fast as it was before the problem started. I got home and took out the plugs. They were all hot (white, coated with ash from the looks of it). At this point I noticed that at idle the car would smoke very noticeably. It also spit a little liquid out (I can't tell exactly what it is), but it did a little bit of this since I bought it back in September anyways. That reminded me that ever since I bought the car it would smell like gasoline when I floored it, the PO blamed it on the rich tune (~10.5 AFR's), the PO also said he suspected the valve seals to be going.

Not sure what the problem could be I took it out for another drive and kept my eye on the wideband. It would creep down to about 13 as I got into throttle, and then shoot way up into the red "---". I found on YouTube a test to check the UEGO sensor. It involved taking a cloth sprayed with brake cleaner wrapped around the sensor. I did the test and sure enough my UEGO sensor was shot. I ordered a new one and was going to replace it and see if the problem would get better, but now I'm thinking it's something internal to the motor. I don't want to waste a brand new sensor if it isn't the problem (that way I can get my money back, remember I'm a poor college kid).

So what do you suspect the problem to be? What should I check next? It's been recommended that I get a leakdown test done, but I don't have the tools and don't know where to bring the car to get it done. At this point I think I'm going to take it to a shop so they can figure out what's wrong, but what should I check first? If I could diagnose the problem myself and save some money, that would be awesome.

Once I figure out what the problem is, I want to save as much money as possible. I found a long block locally for $650 with 64,000 miles. Part of me just wants to swap that in and call it a day. I don't want to build the motor because I've heard the stock motor is good to about 250 whp, and I do not plan to exceed that. I feel as if I can swap the motor myself with some friends, but I don't have the confidence to take the motor apart myself and say, replace and head or headgasket.

Once I find out the problem, I would love to switch to a Megasquirt and some 550 injectors because it seems like I'm currently running on a cheap system with a piggyback, 305's, and the BEGI FMU.

Sorry for the long post, hopefully you guys can help an eager to learn noob out. I am not very familiar with things motor related, especially internally, but I try. Any input is appreciated.
_spyder is offline   Reply With Quote
Old 05-17-2011, 10:46 PM   #2
Junior Member
Thread Starter
iTrader: (5)
 
Join Date: May 2010
Location: Wisconsin
Posts: 384
Total Cats: 1
Default

So I had a chance to go home and look at the car today.

I started her up, and about 30 seconds later smoke was puffing out with what looked like a blueish tint. I also noticed my oil pressure gauge had dropped to the bottom. Great, looks like she's burning oil.

I'm going to have her towed to a shop tomorrow to have a leakdown test done.
_spyder is offline   Reply With Quote
Old 05-17-2011, 11:58 PM   #3
Senior Member
iTrader: (14)
 
Join Date: Aug 2008
Location: Tinley Park, IL
Posts: 1,488
Total Cats: 0
Default

It's a big difference between being drivable and running right. Those compression numbers are terrible. Did you hold the throttle plate open while cranking? The fact that its low on power and smoking aren't good signs either. The scary thing is if your wideband was reading properly, it could have went lean in boost and caused some serious damage.

As long as your timing belt didn't slip a few teeth and your cam timing is off, which I doubt because of the other symptoms, your looking at some major repair. Best case scenario is it could be a head gasket as long as its not smoking like crazy. Worst case scenario is that it detonated and cracked the rings or blew the ring lands off the pistons. A leak down test might help you isolate it a little better. As long as it's not losing compression through open valves(cam timing off), Expect it to be the head gasket, rings or pistons.

Either way, its going to be a pretty big job and possibly need internal parts and machine work. If you don't feel comfortable doing either, transplanting a different short block may be the better option as long as you can trust the seller's description.

If you do feel like taking a crack at it , grab a service manual and read through it so you have a better understanding of what you are getting into.

Last edited by lordrigamus; 05-18-2011 at 12:13 AM.
lordrigamus is offline   Reply With Quote
Old 05-18-2011, 12:30 AM   #4
Elite Member
iTrader: (12)
 
Join Date: Sep 2007
Location: Charlotte, NC
Posts: 6,868
Total Cats: 66
Default

A) Why the hell did you not remove the damn injector relay and hold the throttle open? Yes, it makes A HUGE ******* DIFFERENCE.

B) You're in Wisconsin. It's cold there. You'll see a ton of cars will exhale moisture from the exhaust when it's cold. This is water that is in the air the engine sucks in and gets compressed and condenses in the warm exhaust gas against the colder exhaust pipe. Hell, I saw cars doing this the other day in low 60* weather. Just because you see something "wet" from the exhaust doesn't indicate a problem.

C) Burning coolant smells sweet.

D) Have you not pulled the dipstick to check the color/condition/smell of the oil?

E) Have you checked the coolant res. for discoloration? Have you run the car and looked to make sure there is no bubbling/pressure in the res.?

F) Have you thought about the possibility of a bac coil?

G) I just wanted to have a point for the letter G.
Doppelgänger is offline   Reply With Quote
Old 05-18-2011, 01:32 AM   #5
Senior Member
iTrader: (14)
 
Join Date: Aug 2008
Location: Tinley Park, IL
Posts: 1,488
Total Cats: 0
Default

I am reading fail. By all means, do what Doppel said and retest with the throttle plate open and injector relay unplugged. You will get a different reading. Then go from there. If its a head gasket the oil will probably be frothy and look like chocolate milk due to it having water in it.
lordrigamus is offline   Reply With Quote
Old 05-18-2011, 04:52 AM   #6
Junior Member
Thread Starter
iTrader: (5)
 
Join Date: May 2010
Location: Wisconsin
Posts: 384
Total Cats: 1
Default

Quote:
Originally Posted by lordrigamus View Post
It's a big difference between being drivable and running right. Those compression numbers are terrible. Did you hold the throttle plate open while cranking? The fact that its low on power and smoking aren't good signs either. The scary thing is if your wideband was reading properly, it could have went lean in boost and caused some serious damage.

As long as your timing belt didn't slip a few teeth and your cam timing is off, which I doubt because of the other symptoms, your looking at some major repair. Best case scenario is it could be a head gasket as long as its not smoking like crazy. Worst case scenario is that it detonated and cracked the rings or blew the ring lands off the pistons. A leak down test might help you isolate it a little better. As long as it's not losing compression through open valves(cam timing off), Expect it to be the head gasket, rings or pistons.

Either way, its going to be a pretty big job and possibly need internal parts and machine work. If you don't feel comfortable doing either, transplanting a different short block may be the better option as long as you can trust the seller's description.

If you do feel like taking a crack at it , grab a service manual and read through it so you have a better understanding of what you are getting into.
Okay, now it runs smooth but I don't want to drive it due to the smoke and low oil pressure before I do further testing. I believe the wideband to be giving false readings based on the test I did for it and have a new sensor sitting in the garage. I'll check the timing, but at this point it's doubtful like you mentioned. Leakdown test will follow. I don't trust myself ripping apart the motor yet, but I feel more comfortable swapping in a used one.

Quote:
Originally Posted by Doppelgänger View Post
A) Why the hell did you not remove the damn injector relay and hold the throttle open? Yes, it makes A HUGE ******* DIFFERENCE.

B) You're in Wisconsin. It's cold there. You'll see a ton of cars will exhale moisture from the exhaust when it's cold. This is water that is in the air the engine sucks in and gets compressed and condenses in the warm exhaust gas against the colder exhaust pipe. Hell, I saw cars doing this the other day in low 60* weather. Just because you see something "wet" from the exhaust doesn't indicate a problem.

C) Burning coolant smells sweet.

D) Have you not pulled the dipstick to check the color/condition/smell of the oil?

E) Have you checked the coolant res. for discoloration? Have you run the car and looked to make sure there is no bubbling/pressure in the res.?

F) Have you thought about the possibility of a bac coil?

G) I just wanted to have a point for the letter G.
After being told I didn't need to touch the injectors, I did not unplug them or the harness. I did hold the throttle open though, I believe.

Yes, I do live in Wisconsin, but I know when the car exhales moisture rather than spitting black crap since the day I bought it last year.

The exhaust fumes smelt oily, not sweet.

I've pulled the dipstick many times, oil is a little lower, and dark. Oil was changed ~1,000 miles ago.

Also checked the coolant res, nothing abnormal. Radiator also does not bubble.

Yes, a bad coilpack came across my mind. Had the ignition system checked, found nothing.

Quote:
Originally Posted by lordrigamus View Post
I am reading fail. By all means, do what Doppel said and retest with the throttle plate open and injector relay unplugged. You will get a different reading. Then go from there. If its a head gasket the oil will probably be frothy and look like chocolate milk due to it having water in it.
The oil doesn't look like that, I'm doubting the headgasket at this point, but we'll see.

Thanks for the input guys, still learning mechanics. I have learned tons about cars in the last 3 years though.
_spyder is offline   Reply With Quote
Old 05-18-2011, 09:35 AM   #7
Elite Member
iTrader: (12)
 
Join Date: Sep 2007
Location: Charlotte, NC
Posts: 6,868
Total Cats: 66
Default

I'd grab another coil since they're easy to find, cheap and easy to replace and give it a shot. I had a coil with intermittant problems and the misfire you speak of fits the description. Does your car have a cat. converter? Mine spits out plenty of soot....enough that over the months a black shadow has appeared in my garage/driveway from starting the car every day. It's not a metric ton, but it's there and I can see it...and since it's always been there (even on my new- literally- engine) I know it's normal, esp. on a turbocharged car running a bit richer. Since you indicated that you had seen 10.5 AFRs, I'd say that soot/water mix is normal and you should eliminate it from being any kind of problem. Don't forget that when you have the misfire condition you are dumping raw fuel into the exhaust and that will condense like water. Lastly, with compression numbers like you posted, there is no way you had the throttle all the way open....if you honestly know for a fact you did, you're engine is royally fucked.
Doppelgänger is offline   Reply With Quote
Old 05-18-2011, 06:35 PM   #8
Junior Member
Thread Starter
iTrader: (5)
 
Join Date: May 2010
Location: Wisconsin
Posts: 384
Total Cats: 1
Default

Quote:
Originally Posted by Doppelgänger View Post
I'd grab another coil since they're easy to find, cheap and easy to replace and give it a shot. I had a coil with intermittant problems and the misfire you speak of fits the description. Does your car have a cat. converter? Mine spits out plenty of soot....enough that over the months a black shadow has appeared in my garage/driveway from starting the car every day. It's not a metric ton, but it's there and I can see it...and since it's always been there (even on my new- literally- engine) I know it's normal, esp. on a turbocharged car running a bit richer. Since you indicated that you had seen 10.5 AFRs, I'd say that soot/water mix is normal and you should eliminate it from being any kind of problem. Don't forget that when you have the misfire condition you are dumping raw fuel into the exhaust and that will condense like water. Lastly, with compression numbers like you posted, there is no way you had the throttle all the way open....if you honestly know for a fact you did, you're engine is royally fucked.
The misfire has disappeared and hasn't come back for the past month or two. Not sure what the case is there. Yes, the car has a Magnaflow catalytic converter and your description fits mine pretty well. That is one less thing to worry about then. I'll try to get a compression tester again and do the test with the injectors off and throttle open, because the car doesn't run like ****. It actually runs smooth, just with very low oil pressure and a bunch of blueish smoke. I'll see if I can get a video up on here soon.
_spyder is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Need help - Stock Balancer and Fastforward overlay pulleys Frank_and_Beans Supercharger Discussion 13 09-12-2016 09:17 PM
Mazdaspeed 2.0L C-Spec ITB motor w/ accessories graexodus Miata parts for sale/trade 9 10-25-2015 04:34 PM
Bad head gasket or ? shooterschmidty Engine Performance 8 09-30-2015 11:28 PM
WTB HPDE miata - Texas Voltwings Cars for sale/trade 0 09-27-2015 07:40 PM
another noob kr307 Meet and Greet 1 09-26-2015 11:33 AM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 06:48 PM.