I have a 454 big block Chevy that I purchased from a guy online. It looked good, we pulled the valve covers and it had a hydraulic roller cam and a set of Trick Flow aluminum heads with a Summit Racing dual plane intake. We dropped it into my boat, test fired it, and after about five minutes of running time we noticed the lifters started clattering. We pulled the valve covers and the oil looked milky, meaning we have water in the oil.
We pulled the intake manifold and the RTV seal at the water crossovers looked good. We also pulled one head and the gasket looked fine with no indications of a leak. The only thing we noticed was that whoever put the engine together did not put any thread sealer on the head bolts. There was water on about half of the head bolts above the threads. Would this be enough to put that much water in the oil?
You have found your problem. Yes, it still could be a bad seal between the cylinder head and the block or between the intake manifold and the heads, but our money is on the head bolts.
Bolt Holes Into the Water Jackets
You didn’t mention what era 454 you are dealing with but we’ll safely assume this is a Chevy MK IV big block that has head bolt holes that extend into the water jackets. The later MKV and VI blocks used blind head bolt holes where this would not cause the problem. This is a very common occurrence with many production V8 engines and because of the water pressure in the block, it is essential that you use a thread sealer on every head bolt that is open to the cooling system.
You didn’t mention how you tested the engine but we’ll also assume you had water from your house plugged into the system. A mere 10 to 20 psi is enough to push water past these threads, past the heads of the bolts, and into the interior of the engine. It would not take long for even a small amount of water to turn the oil a milky color.
A Cheap & Easy Fix
The good news is that the fix is extremely easy and will not cost much. We would recommend pulling the other head as well and replacing the head gaskets on both sides with a high quality composition gasket. While the heads are off, it would be a good idea to check for deck straightness with a quality straightedge and a feeler gauge. You should not be able to push a 0.002-inch feeler gauge in between the head and the straightedge. You should check flatness in multiple crossing directions on both heads and deck surfaces just to make sure.
Torque & Other Installation Considerations
You didn’t mention this, but it’s also entirely possible that if the engine assembler did not put sealant on the threads then he probably also did not place lube under the bottom of the head bolt. This is important because roughly 50 percent of the torque required for a bolt of this type is used up in overcoming the friction between the back side of the head bolt and the head. If the head bolt is dry, this radically increases the friction in this area.
This may not sound all that important, but an increase in friction here along with dry threads increases the friction in both areas. When torqued to the specification—let’s say 65 ft.-lbs., this means that far less tension is applied to the bolt to create the proper clamp load on the gasket. It’s difficult to offer a number but the clamp load on the gasket could be reduced by 20 to 30 percent because of this oversight.
Proper Reassembly Procedure
Now let’s work on the solution that will prevent this from happening again. First of all, make sure the threads in the block are not filled with rust or debris. It’s best not to use a regular tap for this since it will actually remove metal from the female threads. ARP makes what it calls a clean-out tap that is specially sized to clean debris but not remove metal. We’ve listed the sizes and part numbers in the accompanying chart.
You didn’t mention what head bolts you are using, we’ll assume they are aftermarket bolts since the Trick Flow heads use three longer bolts on the exhaust ports because the ports have been raised. We’ll also assume they are ARP fasteners (although this procedure is the same regardless of which bolt you are using).
After the threads in the block have been cleaned with the ARP tap and the gasket and heads have been installed. Make sure the spot-faced area where the head bolt contacts the head is completely clean and dry. Place a decent amount of thread sealer on the threads of each head bolt. Assuming you are using head bolt washers, make sure the bottom side of the head bolt washer is also clean and dry.
Place a small amount of ARP Ultra-Torque on the top side of the washer. If you are using ARP head bolts, the washers will have a radius that fits the radius of the inside diameter of the bolt head. It’s critical to make sure the washers are installed correctly and there is Ultra-Torque between the washer and the underside of the head bolts. What we are doing is making sure the head bolt washer does not turn when the head bolts are tightened.
If the washer turns, this converts it into a bearing, reducing the friction which will place excessive torque into the bolt that could easily pull the threads right out of the block—which we want to avoid.
With lube under the bolt head, now we can begin the torque process. The ARP torque spec is 70 ft.-lbs. which should be applied in three equal steps in a rotational pattern starting in the center of the head. We’d suggest starting at 30 ft.-lbs., then going to 45 ft.-lbs., and ending with the 70 ft.-lbs. spec. This larger jump on the third pass will ensure a proper movement of the head bolts to create the required clamp load. This will evenly load the head gasket and prevent it from leaking.
Another real possibility is that the head gasket allowed coolant or water to leak into the engine. It’s possible that the head bolts were improperly torqued or that the bolts were under-torqued. This happens because the torque wrench has not been calibrated in a long time (if ever). A non-calibrated wrench could easily report torque far below the 70 ft.-lbs. required. All the above steps will help.
Another indication of a weak clicker torque wrench is if the user leaves the torque setting applied and does not return the adjustment back to its lowest setting. We performed a test where we left the torque setting at 65 ft.-lbs. for 60 days and the wrench lost almost five percent accuracy. What this does is weaken the adjustment spring that triggers the audible click. Leave it at the high setting for a year and the wrench could lose 10 percent of its rated setting. A loss of 10 percent at 70 ft.-lbs. drops the torque to 63 ft.-lbs.
It’s also possible (although unlikely) that the leak originated from the intake manifold which means we would recommend using a new intake manifold gasket. There is a procedure for checking for proper manifold sealing that we’ve already outlined in an earlier tech column, so we won’t run through it here, but it’s worth the effort if you think the intake may be leaking coolant into the lifter valley.
Ask Away! Parts List
- ARP 7/16″-14 clean out tap, ARP-911-0004
- ARP tap kit, set of 5, ARP-911-0006
- ARP head bolts, BBC w/aftermarket heads, ARP-135-3607
- ARP thread sealant, ARP-100-9904
- ARP Ultra-Torque lubricant, ARP-100-9908
- Fel-Pro performance head gaskets. FEL-1037
Production Gen VI BBC blocks do not have blind head bolt holes. I just went through a similar issue of them leaking from using the incorrect thread sealer.
Jeff: It goes even farther: all factory big blocks (MkIV, V, VI and L18 8.1L) have wet head bolt holes, except the Mark IV Bow-tie block (including Mk IV 502), Mk V and VI 502, and the Bow Tie blocks current from GM Perf Parts. Cannot answer for any aftermarket blocks (Brodix, Dart, etc.). The real reason the big bore Bow tie blocks have blind holes was due to the cylinder wall thickness for (origianlly) strength and then to allow finished cylinder bores over 4.375 inches, expample: 502’s at 4.47 roughly).
First! Make sure that when you ran the engine with the water hose attached, you did not leave the water on with the egine not running. That will force water in the exhaust and past the exhaust valves.
Once you get the water problem fixed the rest of the water in the engine will start steaming out when the temperature comes up to 180 degrees.
Great idea for any open bolt holes on any engine no matter what brand it is.
Typical manifold seal issue.
More related to factory iron heads. Exhaust guides can crack above the guide in the water jacket. Water seeps through the cracks and down the guide dripping onto the open or closed exhaust valve and into the cylinder. It may or may not get into the oil but it can sure stick a piston if it sits in the cylinder. Always change the exhaust guides when BB heads have been overheated.
Hi so I have a 1993 7.4 gen v mercruiser in my boat the engine is FWC. So I had the motor rebuild put back in and took a sea trial that’s when the motor was leaking out the back of engine between head and block. So builder came to me and removed intake manifold and heads brought back to his shop and cleaned everything and resurfaced the heads and brought it back put it together and took for a ride and now it is leaking antifreeze while sitting? Can’t figure this out and the builder say he never had this happen.
So it is also leaking by the water jackets on the intake there are little puddles sitting there and this engine hasn’t run since October
Need some input please
I just finished rebuilding a 496″ BBC and had a minor oil leak at right rear corner of oil pan. Engine is on a break in stand and I have been running it to identify and repair leaks plus get it broken in before I put it in my 64 C-10. I removed the pan with engine on the break in stand to replace the gasket (and put a little more RTV in the corners) and I noticed some milky white fluid inside the pan just behind the front pan gasket. I know this is water getting into the pan but I am not sure where it is coming from. My guess is the head bolts in the front of the engine since that is where I see the mixture. Milky fluid seems to be entering the pan right behind the front pan gasket, then running back toward the sump. (I have a photo if you would like to see it, just let me know where to send it to). I am using a set of aluminum heads from Skip White and ARP head bolts. I thought I followed the directions accurately, but I also thought there were only certain bolts that passed through water jackets. In reading about this it seems ALL bolts pass through water jackets. Is this true? If so I may need to go back and apply the ARP sealant to all the bolts. Is there a way to determine if my leak is due to water getting past the head bolts vs. head gasket vs. manifold gasket?