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how much loss of power from leaky head gasket/cracked head? 

 

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 Post subject: how much loss of power from leaky head gasket/cracked head?
Posted: Fri Jan 19, 2007 1:42 pm 
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My engine's head is leaking water outside the head/block under cyl #2, running on LPG and its an EL 5 speed manual 6 cylinder.

About 3 months ago I dyno'ed my car and got 119kw with an ED XR6 cam, the engine was losing about 500ml of water per month or thereabouts.

I just changed the cam for an Alted stage 1 thats been sitting around here for a year or so. The moment I changed the cam, it felt like it was considerably more powerful around 2500-4000RPM, this is from the seat of the pants testing.

So I put it on the dyno again, now its losing about a litre of water per week, so much so that after 2 ramp ups from 1500rpm to 5500rpm in third gear, the low water warning light on the dash illuminates and I need to top it up. There's a s**t of water under the car on the dyno.

Whats worse is I've now only got 111kw yet the car feels s**t quicker. I CBF putting the other cam in and redyno'ing the car.

Now, question is, should I be losing that much power from a small leak on the side of the head? I understand 1 dead cylinder is 1/6th of the power (about 20kw) but when I pull the spark plug from one cylinder, the engine vibrates more than a jar full of angry sandflies in sunlight so its not like the cylinder is "dead" per se, its still giving out power to keep the engine smooth (for a ford six at least). A new cam should be a kw or two more per cylinder, minus a dodgy cylinder, I should have about the same amount of power.... I mucked around with the timing, ensured the mixtures were stoich and everything else seemed just right...

What gives?
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Posted: Fri Jan 19, 2007 2:01 pm 
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lol

I could write a page long post with the answers to your questions, but instead I will just point out the obvious - you have a blown head gasket and you need to fix it.

 

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Posted: Fri Jan 19, 2007 2:04 pm 
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stockstandard wrote:
lol
you have a blown head gasket and you need to fix it.


Gosh darn really? :)

Gimme that page long explanation.
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Posted: Fri Jan 19, 2007 2:17 pm 
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If compression is up s**t creek in one or more cylinders... or better yet, if its throwing a bit of coolant/water into the combustion equation... it comes as no suprise that the power is down!!

Done a compression test?

Does the cylinder near the leak look unusually clean inside (spark plug a good indicator)?

 

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Posted: Fri Jan 19, 2007 2:20 pm 
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Plugs look dead set identical (compression could be leaking between cylinders and only pushing water outside but not sucking it in maybe?)

Might go outside and do a CR test....
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Posted: Fri Jan 19, 2007 2:32 pm 
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I think i have the same problem, but oil, and prolly coolant too, it idles rough as a mofo for first 20 secs after turning it on, i rekon theres a lack of power, it could just be me being sick of a gutless car but i think theres a lack.

I just bought a tickford head, for $400 on ebay, replacing the head gasket and head at same time, about $7-800 for more power, rather than $600 for the same.

 

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Posted: Sat Jan 20, 2007 7:50 pm 
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CR test between 160-170 on all pots.

I might just swap the cam and run it on the dyno again to see how much less power I have with the older cam...
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Posted: Sat Jan 20, 2007 7:52 pm 
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Seannyb wrote:
I think i have the same problem, but oil, and prolly coolant too, it idles rough as a mofo for first 20 secs after turning it on, i rekon theres a lack of power, it could just be me being sick of a gutless car but i think theres a lack.

I just bought a tickford head, for $400 on ebay, replacing the head gasket and head at same time, about $7-800 for more power, rather than $600 for the same.


I dont have any symptoms other than loss of power and loss of water. Oil is fine, spark plugs are identically colored.

I dont understand how I could lose so much power yet the engine is still smooth. It should be as rough as a VN 3.8 in perfect tune...
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Posted: Sat Jan 20, 2007 8:59 pm 
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if ur seapin water outside of the head, uve done the gasket simple as that, replace and dyno it with the alted to get a good stats increase :P

 

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Posted: Sat Jan 20, 2007 9:03 pm 
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cooki_monsta wrote:
if ur seapin water outside of the head, uve done the gasket simple as that, replace and dyno it with the alted to get a good stats increase :P


Mate I know i've done the gasket or the head is rooted.

I'm morbidly curious why the engine is still SMOOTH with such a loss of power. I can only see the leak from one cylinder and am assuming no compression leakage between cylinders.

If one cylinder were operating at half power, shouldn't the engine be rougher than normal? This one aint... That is whats getting my goat. I know the head and/or gasket are stuffed.
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Posted: Sun Jan 21, 2007 7:09 am 
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do you have the dyno sheets?
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Posted: Sun Mar 11, 2007 10:11 am 
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To drag up this old post, I found the problem

Not entirely to do with the head gasket, which I now have to top up half a litre per day because it's losing so much water. I did some more playing with the timing and I just got 124rwkw.

The problem? LPG running very rich. Leaned it out to get good AFRs and the power rocketed up.
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