Kent Engine Failure - Help with Diagnosis

[-pru-]

On Sunday, I arrived in Lincoln, NE for the SCCA Solo Nationals. Activities for the day included unloading car (85 DB1 Kent) from trailer and driving the it to/from Tech; car performed flawlessly. Loaded car back into trailer and called it a day.

On Monday, I unloaded the car with plans to drive it to the event scales. When I hit starter button, I heard a very large knock. Engine didn’t budge. Put it in 4th and tried to rock car but no luck. Pulled #1 plug and did an ignition off crank; coolant shot to the ceiling of the trailer confirming my suspicion; engine had hydro locked. Gave up trying to figure out what went wrong at that point...

Now that I'm home, I'm trying to diagnose what happened. I started by pulling the cylinder head. When I removed the intake, I found coolant on the back side of the intake valves of cylinders 1, 2, and 4 (3 was dry). All the noted cylinders had coolant from the back side of the valve up to the intake port (i.e. a LOT of coolant). Next pulled valve cover; top end looked perfect. When I finally removed head, I found coolant in ALL cylinders. The head gasket looked fine, but the bottom of the head was wet...

At this point, I'm stumped. I would say it's a warped cylinder head, but I cannot get a good read on that idea with just a straight edge. The overnight failure seems super odd to me as well; why fine one day and dramatically fail the next....

Attached a few photos for reference...Any help would be appreciated.

[kevskisps]

What about the inlet manifold gasket or face? i.e. there is a water passage in the middle/bottom to heat up the manifold in it's original destination and that we normally block up. Is or the passage in the manifold leaking into the inlet side of the engine then causing the lock. Remember this side is under 5-10 PSI when the engine is up to temp?

Was no. 3 valve open at rest when you took it apart and may explain why it was dry and the others had backed up with water?

[kevskisps]

Just noticed it's an alloy head.

Worth looking this thread just in case similar issue

https://www.apexspeed.com/forums/sho...highlight=leak

[BeerBudgetRacing]

Just noticed it's an alloy head.

Worth looking this thread just in case similar issue

https://www.apexspeed.com/forums/sho...highlight=leak

That's his original thread.....

[t walgamuth]

On Sunday, I arrived in Lincoln, NE for the SCCA Solo Nationals. Activities for the day included unloading car (85 DB1 Kent) from trailer and driving the it to/from Tech; car performed flawlessly. Loaded car back into trailer and called it a day.

On Monday, I unloaded the car with plans to drive it to the event scales. When I hit starter button, I heard a very large knock. Engine didn’t budge. Put it in 4th and tried to rock car but no luck. Pulled #1 plug and did an ignition off crank; coolant shot to the ceiling of the trailer confirming my suspicion; engine had hydro locked. Gave up trying to figure out what went wrong at that point...

Now that I'm home, I'm trying to diagnose what happened. I started by pulling the cylinder head. When I removed the intake, I found coolant on the back side of the intake valves of cylinders 1, 2, and 4 (3 was dry). All the noted cylinders had coolant from the back side of the valve up to the intake port (i.e. a LOT of coolant). Next pulled valve cover; top end looked perfect. When I finally removed head, I found coolant in ALL cylinders. The head gasket looked fine, but the bottom of the head was wet...

At this point, I'm stumped. I would say it's a warped cylinder head, but I cannot get a good read on that idea with just a straight edge. The overnight failure seems super odd to me as well; why fine one day and dramatically fail the next....

Attached a few photos for reference...Any help would be appreciated.

I'm very sorry you are having this trouble Chris. Just two comments:

1. A straight edge should be good for measuring for warp. I don't know of any other way. You have to move it around and check longitudinally and crosswise.

2. The overnight fill up of the cylinder is to be expected with any breach in the head gasket seal. The coolant is under some pressure so a small opening would allow coolant to bleed out until the pressure is equalized.

I am having trouble visualizing how you can have so much coolant in the intake and around. It would seem to me there is not that much coolant in the system to begin with.

[problemchild]

One of my pet peeves about the FF rules is that you are allowed to put epoxy in the water passageway in the intake manifold and then reshape the ports within the intake manifold so that you are now into the epoxy. This can be a potential spot for coolant to leak into the engine cylinders. Often people stick a thin piece of sheet metal in as a blocker plate at the intake manifold gasket but it can move or fall out when doing maintenance. Perhaps your mystery problem is related to this issue.

[Roland V. Johnson]

Every alloy head I have seen does not have a coolant passage into the intake manifold. If there are no apparent head gasket leaks have the head pressure checked to see if you have a crack, or corrosion inside the head. The exhaust ports can be a problem particularly with over porting. If the engine has been sleeved you can also have a sleeve leakage issue.

[Roland V. Johnson]

If that is an Ivey Engine give them a call and discuss the problem with them. 503-255-1123

[-pru-]

Thanks to all that replied publicly and privately; it's greatly appreciated. Lots of good suggestions and/or recommendations. I'm still at a loss as to exactly what happened, but it's time to move forward.

Given the issues I have experienced this year (i.e. multiple head related failures), I've run out of patience trying to fix this engine. I'll pull / prep it for shipment to Ivey for a rebuild (that will include a NEW head).

I'll post up if Ivey finds anything definitive, but at this point I'm chalking it up to a head (RFD) that I should have retired after the first failure (pin hole leak in #1 intake that was welded).

Take care,

[TimH]

Jay will make it right.

[stonebridge20]

Jay will make it right.

And or Colin and Cameron.

Those boys need love too.

[captain_pants]

Best of luck, Chris! The whole CM grid was gutted to hear that you left Nationals before running.

I'm sure we could have got you in someone's car. Not the same as running your own, but still...

[lowside67]

Thanks to all that replied publicly and privately; it's greatly appreciated. Lots of good suggestions and/or recommendations. I'm still at a loss as to exactly what happened, but it's time to move forward.

Given the issues I have experienced this year (i.e. multiple head related failures), I've run out of patience trying to fix this engine. I'll pull / prep it for shipment to Ivey for a rebuild (that will include a NEW head).

I'll post up if Ivey finds anything definitive, but at this point I'm chalking it up to a head (RFD) that I should have retired after the first failure (pin hole leak in #1 intake that was welded).

Take care,

No appetite to use this as an impetus to do the Honda conversion? I cannot overstate how nice it is to have such a reliable, understressed, modern fuel injected motor to just make the engine part of a CM effortless and out of mind. I recognize that comes at a cost but given you have such a nicely kept car and one of the few with a factory conversion kit available, it seems worth mentioning.

-Mark

[chrisw52]

No appetite to use this as an impetus to do the Honda conversion? I cannot overstate how nice it is to have such a reliable, understressed, modern fuel injected motor to just make the engine part of a CM effortless and out of mind. I recognize that comes at a cost but given you have such a nicely kept car and one of the few with a factory conversion kit available, it seems worth mentioning.

-Mark

honda conversión is north of $15k while an engine rebuild is around $8k tops. Then with the brutal environment that we enjoy in CM, we can expect an engine to last 10 years or more. Honda isn't worth it.

road racing on the other hand, the Honda reliability would definitely be a factor to consider

[-pru-]

No appetite to use this as an impetus to do the Honda conversion?

...in CM, we can expect an engine to last 10 years or more.

Mark/Chris,

Thanks for the feedback. I considered the Fit conversion, but rejected based on cost/benefit; it's just more than I want to spend and, as Chris notes, a Kent can reasonably be expected to last 10+ years running CM.

I've owned the DB1 since 2006 and, outside of this year, the Kent has been extremely reliable.

The above stated, I can see owning a Fit powered car at some point; just not this one.

Take care,

[-pru-]

DB1 engine update from Ivey; water leak caused by cracked block (crack at the bottom of the water jacket along the cylinders in the crankcase). All other parts (including repaired head) okay. New Ford Racing block will be needed on rebuild. Awaiting formal estimate.

[TimH]

DB1 engine update from Ivey; water leak caused by cracked block (crack at the bottom of the water jacket along the cylinders in the crankcase).

You were never going to get that fixed by yourself...

Silver lining is that you're going to have a great motor soon.

[t walgamuth]

The thing about the fit conversion that is impossible to put a hard value on is the increased value and marketability of a fit equipped car. One of the big attractions of Phil's car was the fit conversion done three years previous. Sell-ability is a bigger factor for an old man like me more so than for some of you young 50 somethings.

[Daryl DeArman]

Sell-ability is a bigger factor for an old man like me more so than for some of you young 50 somethings.

Ha ha! Some of us young 50-somethings have short attention spans, get bored quickly and need to be concerned about sell-ability too.

Personally, if I was to get another "FF" I would not do so with anything but a Fit. It's simply a no-brainer if the conversion was done to a high standard and you are road racing it. If that $20K Piper that just sold had a Fit in it how much do you think it would have sold for?

For SOLO it takes a whole lot longer for that Fit conversion to pencil out. It would take a catastrophic Kent engine failure before most would even consider it. . . like a rod through the block, a broken crank and a trashed head.