possible cracked head

[supraman508]

what are some of the signs of a cracked head cause i have no overheating,just that i have lack of power but Everything else is normal.Would a cracked head give a loss of power?

[jdub]

Yes it would. Do a compression and leak down test. What makes you think it's cracked?
Several things could cause loss of power.

Codes?

Might want to check valve timing to make sure the belt has not jumped a tooth.

[supraman508]

Yes it would. Do a compression and leak down test. What makes you think it's cracked?
Several things could cause loss of power.

Codes?

Might want to check valve timing to make sure the belt has not jumped a tooth.i did a head job in january do to overheating and the engine sounds the same as it did before i did the head job.it has this sound that i can't explain, but if you herd it you would know that it's coming from the head.the head job went perfectly by the way.

[supraman508]

i did a head job in january do to overheating and the engine sounds the same as it did before i did the head job.it has this sound that i can't explain, but if you herd it you would know that it's coming from the head.the head job went perfectly by the way.buuuuut i do get the waterfall when i first start her up and whenever i step on the gas i hear water running behind the dash.i don't understand why i would hear that do to i had no problem with installing the new headgasket.

[jdub]

A cracked head will produce symptoms like a BHG. The difference is exhaust gas gets into the coolant channels through the crack vs the gap/breach in the HG.

You can confirm with a NAPA block tester.

Might want to post up the details on the "head job"...hardware, type HG, machine work, etc. Plus any other symptoms. Playing guessing games is not my favorite thing to do.

One more (and last) time...any ECU codes?

The 7M head is kinda noisy...did you check valve and cam journal clearances as part of your work?

[supraman508]

A cracked head will produce symptoms like a BHG. The difference is exhaust gas gets into the coolant channels through the crack vs the gap/breach in the HG.

You can confirm with a NAPA block tester.

Might want to post up the details on the "head job"...hardware, type HG, machine work, etc. Plus any other symptoms. Playing guessing games is not my favorite thing to do.

One more (and last) time...any ECU codes?

The 7M head is kinda noisy...did you check valve and cam journal clearances as part of your work?what i can tell you is that the head was milled by napa,the headgasket is graphite gasket,waterfall like symptoms when reving the engine,no overheating symptoms.the only code i had was a code 11.Something dealing with a "momentarly interruption in power supply to e.c.u.that was my only code,but that has nothing to do with the lack of power.

[jdub]

Really? A code 11 masks all other codes, so how do you know?

[supraman508]

Really? A code 11 masks all other codes, so how do you know?

i DID NOT know that,but it seem more less then electrical,but then again i'm guessing

[supraman508]

i DID NOT know that,but it seem more less then electrical,but then again i'm guessingI just checked my codes and the only code that shows up is a code 12.RPM SIGNAL.no "Ne" or "g" signal to ECU within 2 seconds after engine has been crankd.Could that code restric power?

[suprarx7nut]

I just checked my codes and the only code that shows up is a code 12.RPM SIGNAL.no "Ne" or "g" signal to ECU within 2 seconds after engine has been crankd.Could that code restric power?

Almost any code relating to the engine could restrict power...

Sounds like your engine doesn't know exactly where it is. That would be a problem.

Check your dizzy connection.

[supraman508]

Almost any code relating to the engine could restrict power...

Sounds like your engine doesn't know exactly where it is. That would be a problem.

Check your dizzy connection.Will do capi:icon_bigg

[87silverbullitt]

buuuuut i do get the waterfall when i first start her up and whenever i step on the gas i hear water running behind the dash.i don't understand why i would hear that do to i had no problem with installing the new headgasket.

I get the "waterfall" and "water running behind the dash" sounds in my supra as well. Can anybody tell me what does that exactly mean???

[enawazh]

Im guessing you have air in your cooling system

[CajunKenny]

I get the "waterfall" and "water running behind the dash" sounds in my supra as well. Can anybody tell me what does that exactly mean???

Air in the cooling system.

It either just needs to be burped or it indicates a larger problem.

[87silverbullitt]

Air in the cooling system.

It either just needs to be burped or it indicates a larger problem.

Will it do any harm by driving with air in the cooling system??

[AJ'S 88NA]

Will it do any harm by driving with air in the cooling system??Air doesn't cool as well as coolant. Burp it or cut the jiggler valve off the thermostat.`Are you loosing coolant? If so were is it going? The bigger problem that was brought up is a concern, BHG.

[CajunKenny]

Will it do any harm by driving with air in the cooling system??

Air in the cooling system can leave you stranded on side of the road with the radiator cap blown off and lost somewhere on the highway, coolant all over your windshield, and you standing there with the 'WT' look on your face.

Aside from that, air in the cooling system means un-even cooling and/or "Hot Spots" throughout the coolant path. These hot spots could cause raised EGR/Exhaust Temps, raised temps in the block, and so on...

Plus it's pretty annoying in the winter time to all of a sudden have no heat!

Oh! Do NOT cut off the little "jiggler valve". It's there for a reason. ;)

Plus, if you're in it that far. Just put in a new thermostat.

[jdub]

Kenny - Cutting off the jiggle valve will allow a small flow through the radiator at all times. It does two things: 1) Allows the system to rid itself of air more quickly. 2) Insures there is no pressure build-up behind the thermostat that can hold it closed.

I cut the jiggle valve off every thermostat I install. ;)

[CajunKenny]

It’s been a while since I’ve visited this subject; but, the thermostat prevents coolant flow to the radiator allowing the engine to reach operating temp as quickly as possible reducing engine wear, crud deposits throughout the coolant path, emissions and such… So with the ‘Jiggler’ thingy cut out it would in fact allow air to pass easier; but, would also reduce the warm up time of the engine (and the benefits listed above) because of the now flowing coolant.

The reduced warm up time is negligible I’m sure so I think that the benefit of allowing air to escape easier/quicker out weighs the negative affects of cutting out the ‘Jiggler’ thingy.

Sorry for the mini-novel. I was just sort of thinking out loud there...

In short, Everyone Cut off your Jigglers! ;)

[supraman508]

It’s been a while since I’ve visited this subject; but, the thermostat prevents coolant flow to the radiator allowing the engine to reach operating temp as quickly as possible reducing engine wear, crud deposits throughout the coolant path, emissions and such… So with the ‘Jiggler’ thingy cut out it would in fact allow air to pass easier; but, would also reduce the warm up time of the engine (and the benefits listed above) because of the now flowing coolant.

The reduced warm up time is negligible I’m sure so I think that the benefit of allowing air to escape easier/quicker out weighs the negative affects of cutting out the ‘Jiggler’ thingy.

Sorry for the mini-novel. I was just sort of thinking out loud there...

In short, Everyone Cut off your Jigglers! ;)Anywayzz i found a retired mech that used to work at a toyota dealership back in the day when when 7m's were DISLIKED MORE by cops :biglaugh: but he told me that he would have christine running like new.so i'm gonsa just give it to him and say HAVE FUN

[CajunKenny]

Hopefully he remembers everything! ;) Many a 7M has been messed up by various shops/mechanics.

There aren't many folks that I would let wrench on my car; but, if you trust him, he knows the 7M, and he does good work, I would treat him well because he'll be worth it! :)

[crisp]

It’s been a while since I’ve visited this subject; but, the thermostat prevents coolant flow to the radiator allowing the engine to reach operating temp as quickly as possible reducing engine wear, crud deposits throughout the coolant path, emissions and such… So with the ‘Jiggler’ thingy cut out it would in fact allow air to pass easier; but, would also reduce the warm up time of the engine (and the benefits listed above) because of the now flowing coolant.

The reduced warm up time is negligible I’m sure so I think that the benefit of allowing air to escape easier/quicker out weighs the negative affects of cutting out the ‘Jiggler’ thingy.

Sorry for the mini-novel. I was just sort of thinking out loud there...

In short, Everyone Cut off your Jigglers! ;)

I think you mean "increase" warm up time with coolant flowing... no?;)


(Reduce temp. rise rate... or delay the heating process... or increase the time until up to temp., etc...)

...just actually read everything in the thread... and that struck me as inverted.




-crisp

[CajunKenny]

You got it...good catch! ;) That was my dislexic day. I have one of those about once a week. :biglaugh:

I hope we all know what I meant though. :)

[crisp]

^^^ Yup. I knew what you MEANT!;)


I had a crack in the exhaust plenum once... so coolant would eventually evap out... but NO effect on performance! Kept evaporating more and more rapidly (likely crack grew...) and then I swapped heads. Fresh reman. did great until it dropped a valve seat and stuck a valve in #3! DOH!

...just getting my next head/install back together.

G/L!


-crisp