Bad head gasket or cracked block?

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Bad head gasket or cracked block?

Postby deepsky » Wed Apr 13, 2016 10:30 pm

I've been slowly getting my 92 All-Trac going, and it has a serious coolant problem. Overheats, and dumps antifreeze from the overflow. Fans work, everything seems OK. Per suggestions from others left the radiator cap off, and under acceleration coolant flows out of radiator like a fountain. This means the exhaust pressure is getting into the cooling system, usually caused by a bad head gasket. But doing more research, it seems this may be a cracked block. I'm already intimidated by a head gasket replacement, but don't want to do that only to find out it is a cracked block. Any way to diagnose this before hand?
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Re: Bad head gasket or cracked block?

Postby ChrisD » Thu Apr 14, 2016 5:01 am

Is it a stock gen 2 head gasket? Typically they will fail before a cylinder wall, although anything is possible. I recently cracked my gen 3 block, had similar symptoms. You could do a leak down test, however that will probably only verify things you already know. Basically, you have to pull the head and take a look. Pull it off, see what looks to be the failure point.

I suppose you should also check the oil. If it's murky / frothy / like a milkshake, stop driving it asap as your oil is getting watered down.
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Re: Bad head gasket or cracked block?

Postby deepsky » Thu Apr 14, 2016 6:08 am

Thanks, Chris for your opinion. That's what I'm afraid of. At this point I'm seriously considering swapping out a gen 4 engine. Not a cheap option, but sounds easier than a head gasket replacement, with the possibility that it could be a cracked block anyway.
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Re: Bad head gasket or cracked block?

Postby GT4_DRED » Thu Apr 14, 2016 1:32 pm

deepsky wrote:Thanks, Chris for your opinion. That's what I'm afraid of. At this point I'm seriously considering swapping out a gen 4 engine. Not a cheap option, but sounds easier than a head gasket replacement, with the possibility that it could be a cracked block anyway.

replacing the head gasket isn't that hard to do, compared to an engine swap. Pulling the head will also confirm if the block is cracked and you can also check the block behind the water pump.
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Re: Bad head gasket or cracked block?

Postby deepsky » Thu Apr 14, 2016 10:12 pm

Thanks for your comment. Can you recommend a tutorial for a head gasket replacement? I've seen the one from lovehorsepower, and left me wondering if I'm up to this.
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Re: Bad head gasket or cracked block?

Postby underscore » Fri Apr 15, 2016 2:29 pm

I'd verify that the headgasket is bad or the block is cracked before doing anything else. Stupid question but I'm assuming you've ruled out the thermostat by removing it?
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Re: Bad head gasket or cracked block?

Postby deepsky » Sun Apr 17, 2016 1:54 am

With the pressurization of the cooling system, and the ability of the heater to work, I'm pretty sure it isn't the thermostat. I'm trying to see if there is any way of confirming cracked block versus head gasket. It seems a tear down is the only way.
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Re: Bad head gasket or cracked block?

Postby Smaay » Wed Jul 06, 2016 6:41 pm

did you even do a compression test?
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Re: Bad head gasket or cracked block?

Postby deepsky » Wed Jul 06, 2016 7:37 pm

Thanks for bringing this back up, this problem is very curious. The engine runs very strong, and things seemed to get better for a while. The ejection of coolant quit, and I did an exhaust gas check in the coolant, and it seemed to pass. So, I drove it on and off for a few weeks here, but after coming home on a hot day (90s) and temps were totally normal range, never high, but a few hours later, I'd say about a gallon of coolant was all over the garage floor. I can see it came from the heater hose connection at the firewall. Refilling, and running the engine, a dribble came from that connection, but no volume that could account for what it did before. Weird. I'm back to thinking head gasket allowing a hot spot intermittently to form, and causing boiling which pressurizes things causing the ejection of coolant. I don't know for sure, but something is fubar.

I'm back to considering a JDM engine swap. I'd like to do a ST205 or maybe even an ST246 engine, but it seems like air conditioning wouldn't work. That's a no go for me, so looking at a CS ST185 swap. I just don't know what I'll find inside the engine if I tear it down, and not sure I'm up to the challenge of a head replacement. Any advice is appreciated.
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Re: Bad head gasket or cracked block?

Postby awdmofo » Thu Jul 07, 2016 3:40 am

deepsky wrote:Thanks for bringing this back up, this problem is very curious. The engine runs very strong, and things seemed to get better for a while. The ejection of coolant quit, and I did an exhaust gas check in the coolant, and it seemed to pass. So, I drove it on and off for a few weeks here, but after coming home on a hot day (90s) and temps were totally normal range, never high, but a few hours later, I'd say about a gallon of coolant was all over the garage floor. I can see it came from the heater hose connection at the firewall. Refilling, and running the engine, a dribble came from that connection, but no volume that could account for what it did before. Weird. I'm back to thinking head gasket allowing a hot spot intermittently to form, and causing boiling which pressurizes things causing the ejection of coolant. I don't know for sure, but something is fubar.

I'm back to considering a JDM engine swap. I'd like to do a ST205 or maybe even an ST246 engine, but it seems like air conditioning wouldn't work. That's a no go for me, so looking at a CS ST185 swap. I just don't know what I'll find inside the engine if I tear it down, and not sure I'm up to the challenge of a head replacement. Any advice is appreciated.


Im in the same boat as you right noW :roll:. Just bought myself a 1990 ST185 (212K miles) with what the young kid that owned it before me said was a blown head gasket. He even included a Permatorque head gasket when he sold me the car for cheap. Watched the Love horse power videos a few times and started digging into the car already, im not a tech, no certified whatsoever but, I got the tools and a little experience so i said why not try and fix it before I buy a new motor. Basically I have a very low budget and only bought the car because it was STUPID cheap, and figured I'd be a long term project. I have three choices at this point #1 attempt a fix, remove the head get it clean and tested at a local shop, replace the hoses and gaskets and if everything checks out with the head slap it together and see if it runs. Will cost me less than $500 for everything as I will do most of the labor. If it does run well then i'll be proud I tried and i'll be cruising the streets in no time 8) . Option#2, save a little and buy my buddy's mr2 3S with a blown HG thats already removed from the car and slap that into my car, cost might be closer to $1000+ range. Option#3 save for the rest of the year, sell my first born and buy a ST205 motor and mod the crap out of it and make it a 400AWHP monster. I have 6 weeks of free time and not much money so I think option 1 is the way i'll have to go. Not that im qualified to get a lot of advice, but You can take your car apart at the same time as me and I can help you as you go along. I have a toyota tech that lives next to me so if I get stuck hes only a text away lol.

Look at it this way, even if the block is cracked you'll know once you take the head off, and you'll have learned how to take apart half your engine! you won't be in any worse shape than before because your block would have been cracked already... Just a thought.
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Re: Bad head gasket or cracked block?

Postby deepsky » Thu Jul 07, 2016 6:51 am

I'm still trying to decide what to do...
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Re: Bad head gasket or cracked block?

Postby underscore » Thu Jul 07, 2016 2:26 pm

The coolant temp always spikes after the engine shuts down as it's no longer circulating. When the weathers the same go drive it hard (stay close to home), once it's nice and hot shut it off, pop the hood and wait to see if anything leaks as the temperature rises in the block. Do it a couple times if nothing is happening to be sure. If you're confident nothing external to the engine is leaking (replace/remove the thermostat, replace the rad cap, and be 100% sure it's burped properly) and it's still pushing coolant out then go pull the motor and take the head off of it. If you're considering swapping the engine you're gonna be pulling the motor anyways, so you may as well take it out and find out if it's the head gasket or block before buying anything. If it's the head gasket you should be able to get a machine shop to deck the block and head and reinstall the head for you, then you just have to put the accessories back on and put it in.

I'm always hesitant to suggest pulling the motor as I remember someone on here (or another forum) was overheating and pushing coolant and pulled the motor, completely overhauled it, and then had the same problem. It turned out the rad cap was bad, and all the stuff that just got replaced was for nothing.
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Re: Bad head gasket or cracked block?

Postby ChrisD » Thu Jul 07, 2016 2:54 pm

Have a leak down test performed, and a compression test. Also, do you have coolant in your oil or visa versa?

The answers to those items will give you a lot of insight.

As I mentioned above, I did crack my block. Had frothy oil, could see just by looking in the oil fill cap. I did a leak down test - showed some inconsistencies but wasn't conclusive. Had coolant in the oil, so I knew there was something up. Pulled head. Found crack. Then decided which path to take. For me, it meant a rebuild with a new block. For you, it might mean a head gasket. Or a swap. Budget out the options and pros/cons, but not till you know what's wrong. It really is the best way.
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