URGENT:Leaking HG; Anybody Just Install ARPs without new HG?

DOC4444 · **Posted:** Tue Jun 10, 2014 10:32 am

Geordi and I are tearing into KJ CRD today. HG has VERY slight leak (bubbles in bottle at idle).

Has anyone just gone with ARP studs and NOT replaced HG?

If so, how many miles since/

We need to decide in about 3 hours whether to change HG or not.

THANKS!

DOC

papaindigo · **Posted:** Tue Jun 10, 2014 11:08 am

For what it's worth and geordi already knows this. On stoutdog's 06 we lifted the head to retrieve a broken glow plug time and bolted everything back down with ARP studs using the same head gasket. 4,000+ miles later no coolant leak.

While I don't know personally I suspect that if the head and block surfaces are smooth (e.g. no etching/pitting) and the gasket is in good shape it can be reused. I'm guessing you are close enough to idparts to grab a gasket if needed though.

DOC4444 · **Posted:** Tue Jun 10, 2014 12:07 pm

Thanks for your reply, Pap. Has your son done any towing since doing the ARPs? If so, how much weight and how many miles?

We lost half the coolant in the header tank in just an hour of towing 4000 lbs.

Thanks!

DOC

papaindigo · **Posted:** Tue Jun 10, 2014 12:34 pm

No towing just regular city/hwy driving. Only big towing was from Tempe, AZ to Tallahassee, FL a couple of years ago, way before ARP studs, with ca. 2,500 UHaul 5x8 trailer, kayak on top of CRD, me and him in CRD, passenger seat and back loaded to ceiling. Temp gauge never moved above a bit left of center with Kap's 195F tstat mod including the run at 100F+ from Tempe out of the AZ valley east of Tucson.

DOC4444 · **Posted:** Tue Jun 10, 2014 1:24 pm

If we did not tow, we would not know we that we have a problem.

DOC

OneCheekRider · **Posted:** Tue Jun 10, 2014 1:53 pm

I'm sure Geordi will tell you that we did ARP studs on mine without replacing the HG. No problems a year later...although no signs of mine leaking prior to the ARP studs, I just had Geordi put them in when we did the TB.

Also, thanks for posting this...I didn't know Geordi was in the MA area!

flman · **Posted:** Tue Jun 10, 2014 5:32 pm

i hope it all works out for you, sounds like a few others got away with just studs?

WWDiesel · **Posted:** Tue Jun 10, 2014 5:56 pm

Doc, If the head gasket is already leaking, it may already have a flow path worn into the gasket. I would not take the gamble that the new studs alone would stop the leaking. I would replace the gasket along with the new studs. It would give you piece of mind!!! :2cents:

WW

WolverineFW · **Posted:** Tue Jun 10, 2014 8:05 pm

I know at least one other person on here posted they tried only studs and it only lasted 8 months. Lot of work just to get to the bolts. Not much more to get the head off once you are that far into it.

DOC4444 · **Posted:** Tue Jun 10, 2014 9:42 pm

We replaced the HG. It showed signs of blueing on the passenger side of #3 cylinder, right where the head bolt breakaway torque was only 85/90 lbs ft. On the other side of that cylinder, it took 130/135 lbs ft to crack it free. This appears to be where the combustion gasses were leaking and pressurizing the cooling system.

Thanks to everyone for their input, as always,

DOC

flman · **Posted:** Wed Jun 11, 2014 7:31 am

Now you have piece of mind that you are good to go for as long on the ARP studs hold up for you.

I assume you did totally remove the head to clean things up, vs slip the new gasket underneath?

DOC4444 · **Posted:** Wed Jun 11, 2014 9:36 am

Lifted head with engine hoist with turbo attached. Cleaned pretty thoroughly. Going back together now.

DOC

DOC4444 · **Posted:** Thu Jun 12, 2014 10:23 pm

My local expert thinks that the type of HG used on this motor (metal sandwich) does not require the level of surface cleaning that is needed with a composite style. He said that a little oil residue will not matter. It is all about correct and even clamping pressure with this type of HG.

There was no residual pressure in the cooling system this morning after a night-long cool down, but I forgot to tell my wife to keep the heat on. Will see tomorrow AM after several more drive cycles. If OK, the next issue will be if the varying levels of head bolt seat distortion "squashed" back down to flat, prior to final torque of the ARPs. If all of them are not flat now, the ones that are not now may eventually flatten out, resulting in stud torque becoming uneven and presumably leading to another HG leak.

If we get another 90K miles out of it, will check head stud torque when replacing timing belt, etc.

DOC

papaindigo · **Posted:** Fri Jun 13, 2014 8:21 am

Keeping the heat, presumably cabin heat, on doesn't matter. There is no on/off valve in the coolant lines to/from the heater core so coolant flows thru it at all times per both the FSM and personal inspection (I'm 99.999% sure on the latter). What controls whether heat is supplied to the cabin are the blend doors that route air flow over or not over the heater core.

DOC4444 · **Posted:** Fri Jun 13, 2014 10:41 pm

So, when running the AC, the air is both heated and cooled? Or, there are separate paths for cool vs heated air?

DOC

tjkj2002 · **Posted:** Fri Jun 13, 2014 10:45 pm

DOC4444 wrote:

So, when running the AC, the air is both heated and cooled? Or, there are separate paths for cool vs heated air?

DOC

The blend door either allows incoming air to pass over the heater core or AC Evap,or both in some degree depending on the temp setting you have selected.

papaindigo · **Posted:** Sat Jun 14, 2014 7:12 am

Yep separate paths which I'll admit seems really odd to me and way over complicated since that system design requires both blend doors and direction (defrost, dash vent, floor, etc) doors and associated actuators. In older days there was a valve, manual or electric, in the coolant line to the heater core that controlled how much hot coolant flowed to the heater core; that design does not require blend doors and replacing a bad valve is/was certainly easier than dealing with blend door issues.

LMWatBullRun · **Posted:** Sun Aug 17, 2014 5:37 pm

To answer the original question, I was one of the first people to install ARP studs, and I decided to do so without replacing the HG. So far, with about 12 k miles since, no more coolant leaks.

geordi · **Posted:** Sun Aug 17, 2014 6:47 pm

There was a minor concern after the job as to whether the coolant might still be migrating into the overflow, however I haven't heard from Doc in a while, so I am gathering that the coolant was drawn back in at night and the system was just "breathing" normally with expansion and contraction.

SOME coolant movement into the overflow is normal with expansion on a fully-topped-system, and while I try to get the systems as full as possible when refilling... His had a bit in the overflow from the leak that probably got drawn back in on the first few cooling cycles. If there is an air pocket to start with, that will absorb some of the pressure of a hot engine / expanded coolant... But as it migrates to the bottle, a vacuum will be created on cool-down. If there is any water in the overflow, that will displace the air pocket and eventually completely fill the system. After that point, any expansion will create pressure first, then some coolant in the overflow.

THIS IS NORMAL.

What is not normal is coolant continuing to migrate OUT and not back in when the engine cools, and / or pressure created in a cold-and-vented coolant bottle. If your coolant alarm goes off, top off the bottle and continue driving. If the alarm goes off again in a relatively short amount of time... Obviously that coolant is going SOMEWHERE, and you need to start investigating.

For a fast test if you have a very very minor HG leak, connect a length of tubing onto the overflow nipple under the cap, and run it into a jug of water. If you see bubbles at idle... You *may* have a leak. I do not know if this test is fully definitive, however after replacing Doc's gasket, the water bottle test showed no bubbles at idle, and the bubbles when revving the engine may have been from the air in the system migrating around. We HAD just filled it after all. To my knowledge, it is not bubbling any more.

tjkj2002 · **Posted:** Sun Aug 17, 2014 7:02 pm

geordi wrote:

For a fast test if you have a very very minor HG leak, connect a length of tubing onto the overflow nipple under the cap, and run it into a jug of water. If you see bubbles at idle... You *may* have a leak. I do not know if this test is fully definitive, however after replacing Doc's gasket, the water bottle test showed no bubbles at idle, and the bubbles when revving the engine may have been from the air in the system migrating around. We HAD just filled it after all. To my knowledge, it is not bubbling any more.

Great way to test for a bad cap,about it.A very small HG leak you may never notice,it's when it becomes a bad leak is when you start noticing it via coolant ejecting out the cap and white smoke out the tail pipe.

In a closed cooling system like what every KJ uses(besides '07+ 3.7's) you always must have air in the system that get's compressed(and may get expelled under normal conditions) in the coolant tank when hot.I don't know why some KJ's came with a 16psi cap and all aftermarket caps are only rated at 16psi as the correct psi cap should be 18psi.

URGENT:Leaking HG; Anybody Just Install ARPs without new HG?

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