Thar she blows.....again

jvandyke

jvandyke

True Classic
Weird rattly noise when getting off highway, no power, really rough idle, limped home. Suspect head gasket again. No perceptible coolant in oil. Coolant in reservoir was boiling, heat gauge never got more than 1 tick above 190. No idea. Am going to roll it into the garage and leave it, I need a break.:(
 
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Sounds more like a valve

jvandyke said:
Weird rattly noise when getting off highway, no power, really rough idle, limped home. Suspect head gasket again. No perceptible coolant in oil. Coolant in reservoir was boiling, heat gauge never got more than 1 tick above 190. No idea. Am going to roll it into the garage and leave it, I need a break.:(
Click to expand...

Sounds more like a valve to me. I think you will find low compression on one piston. A leak down test is the only way to confirm. Still, not good news as the head needs to come off. Also check how much blow by you are seeing. Is it more than normal?

Good news (if this is the case) is that the car will still be drivable (once you readjust the ignition timing to get it to idle again) just down on power.

Cheers,
Dom.
 
Will do compression test at some point. How do you check blow by? Head was refreshed this spring by a very good shop FWIW. The only change I made was moving spark plugs around trying to figure out why I had arcing at the boots, put in some older ones but all were correct type. Can't see why that would matter unless one exploded and smashed a valve with it's pieces. Oh well. Noise seems like massive exhaust leak but could be mechanical. Too bad. I thought I had just re-reached that plateau where all was well for a while. Ironically I was cruising down the highway wondering why my temp WASN'T slowly climbing, silently congratulating myself. A minute later it started to slowly climb but no where near danger zone. Maybe the temp sensor is way off and it was melting down and I didn't know it. Boiling coolant in the reservoir has never happened before, even when gauge read hotter. When home, after it sat for a minute, I turned the key on and the gauge read 195ish coolant still boiling away. How could the coolant boil and the gauge read only slightly hot?
 
Uh oh...

About the coolant boiling. If the engine is warmed up, and the coolant reservoir cap doesn't hold pressure, it could boil. But it would have to be more than 200ºF. I can reliably get my coolant reservoir fluid to boil by loosening the cap just after parking a hot car.

If you start the engine cold, leave the cap off and see bubbles in the coolant, it is likely a combustion-to-coolant head gasket leak.

But before you start replacing it, get a cheap IR thermometer from you favorite cheap tool outlet and see if you can verify some of your temps. Your coolant temp sender could be tired or bad, and not indicating the true temperature. The thermostat could also not be opening fully, contributing to an over-hot engine.
 
if it is the gasket again

get the block decked. shadetree just had to take 6 thousands off mine that just had a gasket failure.
 
JEFF... you are a GREAT GUY...

... and why this crap keeps happening to ya is beyond me!

Sorry as well... I bet a bum stat was the cause... but not the effect!

Do take some time off though... work with the boyz for awhile... you need a rest or escape for a bit!
 
I'll make tentative diagnostic sorties as time allows (covert, as my wife is ready to have it hauled away while my back is turned :help:).
Will help son with MR2 and ride my motorcycle to get my fix. Interested to know what happened. It will live again, though maybe not for a few weeks.....or even months.
 
Bad gauge?

Have you considered that you might have a bad temperature gauge in your cluster which is giving you incorrect readings.

I was having an issue where my car's temperature reading was creeping up slowly, sometimes getting into the red zone, sometimes not. I kept thinking that I was having overheating issues. This was very frustrating since I had already installed a new radiator, new water pump, new hoses, new thermostat, new radiator cap, and flushed and cleaned everything. I also just had the valves redone, the head milled, and a performance cam installed so I didn't want it to overheat and ruin anything.

The first thing that I suspected was the temperature sensor in the head. It came installed in the head when I had it redone but it was the only thing left that I hadn't already replaced. So, I replaced it with one that was used but presumed good. The problem remained unchanged so I replaced the sensor again with a brand new one and still had the same problem.

I ended up installing a separate temperature gauge in-line with the hose that goes to the radiator and that gauge held rock solid. I also verified the head temperature by using an infrared thermometer.

After looking at the wiring diagram, the only thing left in the temperature display circuit was the wiring and temperature gauge itself. And, sure enough, after I replaced the gauge, my temperature reading was normal. I couldn't imagine that the temperature gauge, which is just an analog meter, would act like that. But, it did.

Just something to consider since you seem to be having a rash of unfortunate problems which seem to relate to temperature.
 
Good point. When I get it sorted I'll be sure to address the issue with some sort of backup temperature sense system. Either verify that the existing system is accurate and/or rig another.
 
Quick compression test and only 60ish on 3 and 4, nice and high on 1 and 2. I suspect head gasket blew between 3 and 4 again.
 
Likely due to a depression between # 3-4. check the block deck surface for flatness.. it is likely not flat.

Verify that the cylinder head surface is still flat. Once a head gasket has failed like this more than once, it can easily become non-flat.

Less of a possible problem, if there is head gasket fire ring (that steel inner ring on the head gasket) has any over hang into the cylinder, this could also cause a failure.


Bernice

jvandyke said:
Quick compression test and only 60ish on 3 and 4, nice and high on 1 and 2. I suspect head gasket blew between 3 and 4 again.
Click to expand...
 
Yesterday I asked my machine shop buddy about your situation.

He said that of course when you take it apart again, take the head to a machine shop to have it checked for flatness, as Bernice mentioned above.

He also said as Hussein did, you will want to closely inspect the block deck surface for imperfections and flatness.

I said, Yeah that would be of course standard procedure if the engine was here in the shop, but how does a regular guy check that with the engine still in the car.

He says, A home mechanic would use a straightedge and feeler gauges and look for gaps or high spots. If the home mechanic does not have access to the shop manual with the deck tolerances, then the rule of thumb he tells people is .003in (three thousandths) on a small iron 4-cyl and .004in (four thousandths) on an iron V8.

I said, you have a machinist's straightedge that you paid $300 for and send out every so often for calibration, what would a home mechanic use.

He said, tell 'em to go to Home Depot or Lowe's, buy a brand new steel carpenter's square (but not the ones with a clear coat, the clear coat makes them less accurate) and use that for a straightedge. He says that's the closest thing to a machinists straightedge that a regular guy can buy locally. Don't use the one your carpenter buddy has, the one that's been bouncing around in the back of his pickup for the last 15 years.
 
Thanks for asking Dan. I was wondering how I do that. I used a metal level last time around but this time I will dig a bit deeper. Carpenter's square is a good idea. We'll use that on the MR2 which we took the head off yesterday. I was very jealous. That head lifted off like noth'n, compared to mine that took 2 weeks and special tools to get off. Silly Toyotas. If I have to pull the whole engine and drag the block to the shop for decking, well, I guess I have to. I probably won't even touch it for a few weeks. I'm going to hammer on the projects my wife wants done and tinker slowly with the Fiat over the winter. The days of challenging myself to keep it on the road everyday at all costs (sleep) are done! It was a fun 2 years though, I hope to have it rar'n to go by spring.
 
if u are not in a hurry

take the engine out. Send the block to be decked perfectly flat. Have the crank balanced. Have the head shaved down. And what ever else you have wanted to do extra to the engine..... because with multiple basket failures your block is not flat. Period.
 
I will check block thoroughly. I talked to the machine shop that did my head and just did my son's MR2 head (great guys, I bring my boys along because he's so cool and describes stuff). He said he would deck my block with crank and pistons installed if I insisted but he wouldn't guarantee it or anything. Balanced crank, lightened flywheel....yeah, it's a slippery slope I don't really want to go down. I'm pretty happy with the car when it's healthy and just want it back to healthy.
 
Unless the machine shop is using a super-modern machine that grinds heads and blocks flat rather than cuts them, with the right preparation you could leave the crank, rods, and pistons in the block for the decking operation and be "reasonably confident" that debris from the machining operation would not contaminate the lubrication system.

The "right preparation" would be sealing every lubrication system opening and/or passage, and would be sealing each of the cylinders, so that no metal shards from the decking operation can enter. You don't have to worry too much about shards in the cooling passages as these are easily flushed out with flowing water from a hose greatly helped if the water jacket plates are removed.

If you can get away with protecting the lubrication system from contamination, you can save a bundle, because otherwise "decking the block" entails a full disassembly of the engine and replacement of main and aux shaft bearings.
Midwest-Bayless prices:
Aux shaft bng: $25
Std main bng: $43
Thrust bng: $10
Labor: ??

The normal procedure is to remove the crank, rods and pistons and set aside for reuse (assuming no issues), then deck the block, then hot-tank it to remove the debris from the decking operation. But hot tanking will expose main bearings and auxiliary shaft bearings to deterioration from the hot tank solution, so they will have to be replaced.
 
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