Engine Head gasket or what?

Foxbody1988

Member
May 4, 2019
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Fresno
Hey guys i have a few questions i am very lost on. To start the vehicle is a 1988 ford mustang gt. I rebuilt the motor about 4 months ago. Its bored over .30 with aluminium heads, cam, intake. the whole 9 yards just not boosted. I had some issues with compression and pulled the heads off turns out all the valves were shot. they were used svo heads, turbo swirl gt40x heads to be exact. so i changed the gaskets when taking those off. i did all this about 2 weeks ago. The car drove fine until a few days ago. the overflow is foaming and bubbling tons of coolant out. and the car is overheating. To start i only put hose water in it, which i know is not good because of corrosion. However i wanted to run it first before putting coolant in it so i didnt waste any money and then was gonna put coolant in it later. the thermostat is fine i checked that, however i tested my 16 pound cap and its only going to 7 psi. The oil i drained and it looks fine it was not milky how ever it did have some little wave looking patterns in it almost like it was fuel possibly.

so in a nutshell car was running fine after head gasket swap and then randomly pooped on me a few weeks after. There is no 50/50 mix just tap water. water pump is fine, thermostat was tested in a pot of boiling water that was fine and put in the right way. replaced that anyways. and the cap isn't holding 16 psi just 7.


unrelated questions that maybe you can answer. All my spark plugs are white on the tip, i have reason to believe they are to hot and leaning out my motor. they are ngks and the only reason i am running them is because they had the threads that fit my heads. i have a brand new aeromotive fuel regulator and crappy truck junkyard 24 pound injecotrs. i also bought a bbk 24 pound maf tune the whole unit. i just purchased some acel 24 pound injectors brand new tonight. so maybe the injector patterns were messed up ? Does anybody know of what gap and heat to use for the plugs i hear autolite and motocraft for brands not ngk so im gonna switch. the car also seems to just rev but not gonna anywhere at higher rpms. im hoping its fuel considering heads were just resurfaced, and guides were replaced along with 3 angle valve job. compression was tested and good around 150.


here are the specs to possibly help you guys
Machined 302 the original motor just bored .4030 and honed. Cleaned and balanced rotating assembly.
crank ground 10
Forged dss racing e series pistons
Svo turbo swirl gt40x alluminim heads
Svo 1.6 roller rockers
Hasting rings
Clevite bearings
Arp head bolts, connecting rod bolts, oil drive pump shaft, and chromoly pushrods stock length I believe it was 6.250
comp cam timing chain on the circle so it’s neutral
Trickflow track heat intake
24ib injectors
Crower cam 15513
Aeromotive fuel pressure regulator
New oil pump I forgot the brand melling i believe
 
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Hoytster

I don't dare do that to my Knob
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Dec 30, 2002
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As @General karthief said, your first step would be to perform a compression test on each cylinder. Your description of the foamy and overflowing overflow bottle points towards a head gasket issue. You can leak compression gases into the cooling system without contaminating the oil depending on where the leak is..

Can you post a picture of the spark plugs? Most guys I've seen run the Motorcraft AGSP32C or Autolite 3924 gapped @ .052 with those cylinder heads on a mild N/A build.
 

Foxbody1988

Member
May 4, 2019
23
3
13
20
Fresno
As @General karthief said, your first step would be to perform a compression test on each cylinder. Your description of the foamy and overflowing overflow bottle points towards a head gasket issue. You can leak compression gases into the cooling system without contaminating the oil depending on where the leak is..

Can you post a picture of the spark plugs? Most guys I've seen run the Motorcraft AGSP32C or Autolite 3924 gapped @ .052 with those cylinder heads on a mild N/A build.
 

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John Dirks Jr

5 Year Member
Jun 28, 2013
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The plugs look fine to me. I would start by putting the correct coolant / water mixture in and get a new radiator cap so it will allow the proper pressure to build and hold. The pressurized system with proper coolant mixture should not boil over unless there is some significant other problem. Get the cooling system correct before chasing performance or tuning issues.
 

7991LXnSHO

Mustang Master
Sep 1, 2010
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Kearney, NE
NGK plugs are good plugs. A hotter heat range is not able to lean out the air/fuel mixture. They may be hot enough to cause predestination (pinging). But they do not cause the amount of fuel to change.
I have had bad luck with BBK meters dying. Search for jrichker ‘s testing procedure on MAF meters. Or save th elink below. It will save a lot of hassle along the line. MAF testing is #7 on the surging idle list.
How do you know how much pressure the cap holds? I hope that means you have a cooling system pressure testing set. I’d pump up the system when the car is not running and see if it holds pressure or if water starts appearing in a cylinder.