Author Topic: Head/ headgastet /cooling system questoin (Read 8524 times)

busguy71 · « **on:** April 29, 2007, 05:23:59 pm »

I have a 1.6na, I overheated it and blew the coolant reservoir. The motor still runs perfect. I replaced the reservoir, but it seems to be over-pressurizing the coolent system. The new reservoir is leaking out of the cap now. My friend thinks maybe the compression of the motor is leaking into the cooling system due to a failed headgasket/ warped head. Anyone else have this experience? Just want some feedback before I go tearing my engine appart.... dont want to do it if I dont need to! :lol: thanks

(temp fix is a 1/8 hole in the reservoir cap, car still runs like new)

RabbitJockey · « **Reply #1 on:** April 29, 2007, 05:27:35 pm »

you have a bad head gasket, a warped head, or a cracked head. or you could just need a radiator cap. i'd try the radiator cap first. if that doesn't work then you gotta pull the head, take it to a machine shop have them check it for straightness, and do a pressure test on it.

tylernt · « **Reply #2 on:** April 29, 2007, 09:06:01 pm »

I check my heads for warpage with a carpenter's square and a feeler gauge. If you're not sure your square is straight, test it on a mirror or window.

Best case, your gasket is blown. Worst case, it's cracked. In between -- warped -- it's still fixable. There is a place in Seattle that will heat it in an oven and straighten it for a couple hundred bucks.

busguy71 · « **Reply #3 on:** April 30, 2007, 04:23:23 am »

ok I guess I have some work ahead of me. Whats the max you can have the head decked and maintain piston to valve clearance? and will the AAZ head gasket fit my '84 1.6 na? thanks :lol:

bvolks73 · « **Reply #4 on:** April 30, 2007, 04:36:10 am »

I'm having a similar problem and am getting ready to replace the head on mine since it jumped it's time a while back (several thousand kms ago) and had slight valve piston/ valve contact. I'm assuming it's the gasket or head too because it really overheated when the heater core blew (All this in one weekend at 30 below and no garage). Mine only leaks out the cap as soon as I shut the car off, never while it's running. I always thought though that it would have to run hot if it was leaking compression into the cooling system. Mine never runs above half way on the guage.

tylernt · « **Reply #5 on:** April 30, 2007, 07:18:11 am »

Quote from: "busguy71"

ok I guess I have some work ahead of me. Whats the max you can have the head decked and maintain piston to valve clearance? and will the AAZ head gasket fit my '84 1.6 na? thanks :lol:

There is some debate on milling diesel cylinder heads. Some people say no way you can't do that, some people say there's no problem. A better solution may be to send it to Autosport Seattle to have it straightened in a special oven, then you can avoid to whole issue.

rallydiesel · « **Reply #6 on:** April 30, 2007, 07:45:08 am »

I think it isn't recommended because of the harder prechambers and that you need to have the camshaft bearings bored. If the machine shop knows how to do this than it shouldn't be a problem.

burn_your_money · « **Reply #7 on:** April 30, 2007, 07:54:51 am »

How much does a good machine job usually cost?

busguy71 · « **Reply #8 on:** April 30, 2007, 08:06:13 am »

I'm looking to do this as cheaply as possible. Just the minimum amount taken off, not even a valve job, I just need to get this car running NOW. Do you NEED to have the cam bearing caps bored? Even for just a few thousanths of decking? and how much does autosport charge for the straightening?

tylernt · « **Reply #9 on:** April 30, 2007, 08:56:53 am »

When I emailed Autosport in March of '06 it was $100. The website is http://www.autosportseattle.com if you want to get an update from them.

BlackTieTD · « **Reply #10 on:** April 30, 2007, 08:59:17 am »

Quote from: "rallydiesel"

I think it isn't recommended because of the harder prechambers and that you need to have the camshaft bearings bored. If the machine shop knows how to do this than it shouldn't be a problem.

this is the truth. if you bring this up and they look at you funny, keep looking for a shop :lol:

busguy71 · « **Reply #11 on:** April 30, 2007, 12:42:49 pm »

I called one shop and they just wouldnt do the work. They said they use cutting bits and you need a grinding type machine to do that kind of work. I did find another shop that could do it for $75. I'll pop the head off and check it for straightness before doing anything though. Thanks for all the advice!

Vincent Waldon · « **Reply #12 on:** April 30, 2007, 12:46:30 pm »

Yup, because of the pre-combustion inserts the popular wisdom in some circles is that you have to use stones to surface the head rather than the usual milling tool. But, I've heard lots of people say they can be milled, you just have to go slow !

mtnsammy · « **Reply #13 on:** April 30, 2007, 01:53:58 pm »

I had mine done but the shop didn't know the right way. it took 6 tries and 3 heads before they figured it out. It can be done but the right shop is the problem. I would check out the Seattle guys if they have had good luck. My brother lives up there so I will definetly see them on my next visit.

Welding the cracks is very hardwithout filling the oil and water ports. If the shop does not know how to you are wasting time. Also the heads have to be heated very slowly before welding or the cracks come right back. A good machine shop can do this but it is a matter of knowing the machinist. Not a yellow page look up.

busguy71 · « **Reply #14 on:** April 30, 2007, 07:49:25 pm »

as far as welding any crack (if I'm so unfortunate to have any... :roll: ) I know two very highly skilled welders. I'd have them do all the work if only they had a milling or grinding machine! but they dont :shock:

the one shop that said he wouldnt do it told me that it makes a hell of a racket when the cutter hits the hardened surface.