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

We always recommend ARP head bolts or studs over stock or other aftermarket bolts because of the superior thread overlap, allowing solid clamp loads to be applied to older, used blocks. Poor thread engagement with inferior bolts can peel the threads right out of the block. (Image/Jeff Smith)
On small- and big-block Chevys (except for Gen V and Gen VI), the head bolts extend through the deck into the water jacket. If the head bolts are not coated with thread sealer, this can allow coolant to push past the threads and mix with engine oil producing nasty results. So always place sealant on these threads to prevent mixing water with the oil. We put sealant on the threads of one bolt and then roll a second bolt around the first to coat both bolts. (Image/Jeff Smith)

Author: Jeff Smith

Jeff Smith has had a passion for cars since he began working at his grandfather's gas station at the age 10. After graduating from Iowa State University with a journalism degree in 1978, he combined his two passions: cars and writing. Smith began writing for Car Craft magazine in 1979 and became editor in 1984. In 1987, he assumed the role of editor for Hot Rod magazine before returning to his first love of writing technical stories. Since 2003, Jeff has held various positions at Car Craft (including editor), has written books on small block Chevy performance, and even cultivated an impressive collection of 1965 and 1966 Chevelles. Now he serves as a regular contributor to OnAllCylinders.