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coolant leak after first start up

6.3K views 17 replies 10 participants last post by  COPO  
#1 ·
Hi guys. So this weekend I got my new motor fired for the first time. It's a ZZ4 short block with Edelbrock eTec 200 heads. Has a comp xr288hr cam and holley 750 dp. This motor sounds great. I have run the motor for probably 1 hour. I haven't driven the car too much because I still need to install all my gauges in the car.

Today I noticed a small "seep" comin from the head gasket near the #8 cylinder. I also saw some near #7.... Do you guys think i should just retorque the head bolts or chang the head gaskets?

Has anyone used these heads and ran into a problem?

Any help greatly appreciated.

Thanks
 
#2 ·
I'd verify the rear intake manifold bolts are tight first. The coolant could be coming from a leaky intake manifold gasket.
 
#5 ·
Did a pressure test and verified the coolant is coming from rear cylinder head gasket area. Edelbrock recommends retorquing after break in but would this actually cure the coolant seep? The motor sat for 5 years before I fired it. Could that damage the head gasket?
 
#7 ·
Edelbrock recommends retorquing after break in but would this actually cure the coolant seep?
Try what the manufacturer recommends first - an old school trick. Retorque after initial run.
Of course, you've applied gasket sealer/shellac to the head bolt threads as the block holes go into the water jacket.
 
#6 ·
weird things happen when stuff sits around. I would spend the money for new head gaskets. I am not a big fan of re-torquing. As far as i see it, yeah the break in procedure could call for it, but this is not a normal circumstance. You developed a leak. So in my eyes, something was not right from the get go. Maybe at some point, the gasket got pinched somehow, and is probably junk. Not worth risking damage to the head, if it happens to have overheated. You don't want to keep torquing on the bolts more than you have too. Personally even with ARP bolts, i will trash them if have to break an engine down more than 3 times. Even if it is on my dime. For piece of mind, and eliminating a variable, get some new gaskets. Then see if you problem still exists. If it is truly coming from the head, could the head be warped? Or did a parts specialist (LOL) happen to sell you an incorrect gasket?
 
#10 ·
I've got a 396 that was rebuilt by PO, the car sat for years in project state. I bougtht the car and the motor wasn't even broke in yet, first thing I did was pulled the heads, intake and replaced the gaskets. The car ran good and had no leaks, but sitting that long I didn't want to chance climbing or pulling and engine over a new pain job when I got the car done. Gaskets are cheap insurance and easier to do at the stage I was with front clip off. Plus gave me a chance to verify some things about the motor with the heads off. :thumbsup:
 
#11 ·
I would retorque the head and see what happens - don't cost nuthin' (John Blutarski)

Drain the radiator. Following the recommended pattern, break a bolt loose, pull it out, seal the threads, reinstall then torque it back to final spec. Follow the order for all 17, refill rad, reinstall header and fire it up - see what you get. If it leaks nothing lost but some time.

I use Permatex Aviation Form-a-Gasket to seal the threads on the recommendation of my machinist.

FYI - My block is a ZZ4 also. I had it bored and put a stroker kit in it at about 750 miles or so (I'm an idiot) - my machinist wasn't impressed with GM's finish on the decks for gasket sealing, so I had the block decked.

Which head gaskets did you use?
 
#13 ·
Im with Sean on this one..
the SHOULD be NO leak... there is a reason why it is leaking....
And if 'patched' fixed by re torquing it WILL according to Murphies Law come back and bite in in the A55 when u are out in the middle of know where in the middle of the night on a road trip....
Also u will always have that question in the back of your mind, espec when on a road trip in the middle of the night....its this how u want to feel EVERY time u jump in and drive the car?

Murphy is your best friend... listen to him (and Sean) and his laws for a hassle free life style
 
#14 ·
I always use straight water for my break-in just in case you have leaks. If you have a roller motor then a 45 min drive with straight water is used then drained including the block. And of course draining the break-in oil/filter.

I would re-torque the heads. I have gear head friends that have been car guys since the 60's and they have re-torqued with no further problems.
 
#15 ·
I put new heads on my motor that was rebuilt in the 90's and never ran, it had .010 off the deck, heads were decked, and had a replacement .040 or .045 ridiculous gasket on it, ran it with no problems. Pulled the heads, added aluminum heads, and a .025" gasket, I was nervous it would leak being that it was a thinner gasket, and the deck had seen heat cycles, after arp bolts and torquing them to spec, I took the car out and ran it hard, and man did it run good. I was nervous so I crawled under and saw some oil and coolant leaking, I knew it was because of the head gaskets, but it was actually because of the intake. The heads were milled significantly, and the intake didn't quite fit perfectly (it should have been milled to fit) so I re torqued the intake, and still saw oil. It was because of the valve covers, 4 bolts just aren't enough, especially if you have a cammed engine that shakes alot, and if it's a manual, it will back the bolts out. I'm sure it's nothing. I would for sure re torque. It is recommended to re torque after the first heat cycle. I guarantee it's nothing to worry about being it's a GM assembled engine, they know what they are doing.
 
#16 ·
The heads were milled significantly, and the intake didn't quite fit perfectly (it should have been milled to fit) so I re torqued the intake, and still saw oil.
I dont get it.. u knew the heads decking was significant yet never consider the angle the valley cover requires, knew it wasnt fitting and simply torqued down more, placing great stress on the casting which is very likely to crack....which maybe your actual issue

It was because of the valve covers, 4 bolts just aren't enough, especially if you have a cammed engine that shakes alot, and if it's a manual, it will back the bolts out.
Rubbish...If u have the tappet cover gaskets fitted correctly and correct gaskets.. (still prefer cork pre fitted into the tappet covers with a few spots of RTV) they will not leak unless the tappet covers are significantly warped and/ or the bolts are over torqued.
Also having the hold down bolts back off is usually because initial over torquing , not because of "manual" or "shakes a lot because cammed"
And if the bolts still back off a small spot of RTV on the threads then torqued down will hold them in place in a similar manner to a nylock nut.

I guarantee it's nothing to worry about being it's a GM assembled engine, they know what they are doing.
Thats a big statement thats one huge assumption to be made at such an unseen distance.....Did I miss something..here does it state this modded engine is "GM assembled"?
 
#18 ·
Could be worse, I got a hole in the head. Likely I use straight water when I fire up a new rebuilt motor. It ran rough for about 5 sec. A weak cast especially after hardened valve seats were installed. The head could not be repaired, it was rotted, so I got another pair of double humpers.

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