Lost HG on 97 850 GLT. Head milling and associated questions

northsoundvolvo · Post by **northsoundvolvo** » 15 Apr 2011, 16:56

Let me begin, well from the beginning. I sold my 80 244 and decided to look for a reliable wagon for the wife to tote the kids around in. We tracked down a decent shape 180K 1997 850GLT for sale for a reasonable price. It ran and drove fantastically well. The previous owner replaced two exhaust valves in the head and had the receipt for the work. We took the train down to Oregon and drove it 400mi back home. It didnt miss a beat. I had every receipt for the car since it was new and knew it was going to need the PCV system done so I ordered the kit, and picked up a code reader to reset the CEL (secondary air injection, no big deal). We noticed after driving it around town that it was loosing coolant. Hmmmmmmmm.

Tracked it down coming from the radiator and coolant tank cap. I replaced both of those and it was still loosing it somewhere. It was an odd leak, only happening when the car was turned off. You could drive the car 200mi and it wouldnt use a drop. I happened to notice a bit of coolant on the driver's side front corner of the head where the head a block meet and just a touch on the head gasket just on the other side of the exhaust port for that cylinder (cyl 5 I think). I cleaned it off and kept an eye on it and it never returned. It was still mysteriously loosing coolant, although you couldnt see it out of the exhaust and all the spark plugs looked clean as a whistle.

Today, it blew the head gasket right next to that exhaust port. OK, time for a head gasket and prob a head job. Ive got a couple questions.

1) How realistic is it that that head can be milled? I thought I saw that they were next to impossible to mill. Am I going to need to buy a reman head? If they can reman them, then they obviously mill them correct?

2) I would appreciate it if some of you could think out loud. What do you think happened? Warped head? Improper torque reinstalling head and gasket blew? Faulty gasket (long shot IMO)? Unlucky roll of the dice?

3) Im fairly certain any 20V 850/S70 turbo heat will fit correct? This is a 2.4 LPT and I think they are all interchangeable, please correct me if Im wrong.

From here, Im going to take the head off, and have it checked to see if its in spec. I know a gasket and bolts are around $200, but whats a good ballpark to have these heads worked if thats even an option?

Thanks for the wealth of info you have all posted and gathered, I really appreciate it.

Post by **Ozark Lee** » 15 Apr 2011, 22:08

Welcome to MVS,

The heads are all pretty much interchangeable to a degree. The HPT heads have sodium filled valves which is fine for a LPT or a N/A but going the other way won't work for very long. The cams are different as well and I try to keep cams and lifters as a set if I'm putting in used stuff.

Before you rip the head off might I suggest that you go through the leakdown tests and the dye test for exhaust gases in the coolant. It could just be a leak rather than a blown head gasket.

Since the head has been off before you are in somewhat uncharted territory. Any time I pull an aluminum head, no matter what for, I send it out to get it decked before putting things back together. The problem there is that the limits are very tight on an 850 head any the maximum shave you can do is about 0.0196 and that is lengthwise. Laterally it is 0.0078. If it has been decked before you are likely out of metal.

Although I have not used them, many of our members have purchased rebuilt heads from Clearwater Cylinder Heads and have been quite happy. I think their web address is www.cylinder-heads.com . Normally they don't list all of the Volvo heads on the web page but they typical have them if you give them a phone call.

Good luck and keep us posted on your findings and progress.

...Lee

northsoundvolvo · Post by **northsoundvolvo** » 16 Apr 2011, 08:21

Thanks for the reply. The HG is definitely gone, i saw steam coming out where i had initially spotted some of the coolant dye. It initially appeared to be just moist with coolant, which i knew was bad in the first place. But when I pulled over it was spewing out of the same spot. Again, thanks for the info.

northsoundvolvo · Post by **northsoundvolvo** » 07 May 2011, 22:06

Got to the bottom of the issue tonight. I pulled everything apart, down to loosening the head bolts. I broke the first one loose, no problem. Moved to the second one, and.............. NO BOLT! Yup, dip sh!t mechanic that put it back together left a head bolt out. It is the #2 bolt. The one on the drivers side at the very front corner of the head, right where I saw coolant leaking from and where the gasket let loose at. As soon as I finish getting the turbo unbolted, Ill get it off and get it to the machine shop. Im hoping that it wont be warped too bad, but we'll see...

Post by **JDS60R** » 07 May 2011, 22:31

I would replace that head- Clearwaters head is $475 delivered. I would not want the head that lifted without having it mangnafluxed and pressure tested first. With a previous cut and low tech mechanic at the helm previously, I would let the old head go and start with something good.

These whiteblock motors hate a bad pressure cap. Get a new one and a reservoir. Before any long trip warm up the motor and make sure the system has pressure by squeezing the top hose. I keep a spare cap in the trunk as the 22psi it provides is definitely needed by these motors. Make sure the cooling system is free of leaks and performing well . the petcock at the bottomof the rad and the oil cooler on the back of the oil pan are common leaks. I use Gates Powergrip SB clamps to remain leak free. They are the only clamps that stop the leak issues long term at the oil cooler hoses.