Head gasget I think. 11mm block maybe?

[matt-stunt]

A little background for you guys. I recently converted my gas caddy to a 1.6d Turbo intercooled vnt15. So I had it out last night to get some miles on it. Currently I have the vane controller for the turbo hooked up to a choke cable so I can adjust it manually from inside the cab (other plans for that in the future). At first I didn't think it would hurt to push it to 25+ psi for a VERY short period of time while closely watching the EGT which didn't even get above 850 at all yet, pretty much just to see what this thing would do. (I have read that 25psi is still kind of in the safe range for these motors) I only plan on running around 10-15psi daily though.

I took several little test rides but after one particular ride I noticed a little oil leaking from front of the head gasket. So I re-torqued the head and figured I would keep the boost below 15 at all times. I figured if the head lifted already I would re-torque and just run the thing around taking it easy for a little while until I felt like doing a HG.

SO I let the truck warm up for about 15-20 minutes while I was cleaning up the shop, (well kind of warm up beings that it was about 20 degrees F around here last night) coolant temp had a hard time getting above 150 degrees F. Drove it to the gas station about a mile down the road, let it idle there for several minutes. Still not up to temperature which didnt surprise me. Pulled out running great and after 1 mile still not above 160-170 degrees F (I was keeping close eye on all the gauges). At this point I was in cursing mode with the boost regulated below 5psi at about 55mph. This lasted for about another mile until a coolant hose blew. I knew it was a hose right away so I checked the temp gauge and saw around 240 degrees F (possibly more but I don't quite remember because I was trying to pull off the road at that point) which I was very surprised to see beings that a whole mile ago it was still below normal operating temperature. Turns out the Plastic connector on the heater core line blew apart (the one that connects the hose coming out of the head to the hose that goes to the heater core.

My conclusion is that the head lifted and now there is way too much coolant pressure even after the re-torque . I don't see the oil leak anymore though. OR simply an old connector that decided it's had enough and cracked in half. (I’m going to replace the connector this afternoon and see what it does)

I believe this is an 11mm block. (My head bolts accept a 10mm hex allen key, not the 12 point spline tool, and I have only one oil passage in the dead center of the front of my head.) After a little research this morning I'm reading that these 11mm motors are not as durable when it comes to boost as the 12mm motors. I knew there were differences but didn't think it would be much more fragile. I guess I missed that chapter in my research.


So the information I am looking for is a possible diagnosis of my engine instantly overheating. I know it’s possible that the hose blew because of too much coolant pressure due to the head gasket. But I didn't think It would overheat that quickly no matter what.
-It would be great if someone could confirm that my engine is an 11mm engine based on the information provided.
-I read somewhere not to stud these blocks due to cracking. Can someone please confirm this is true and let me know what I can do to make the head stay on a little better?

Please don’t bash me for Turboing an NA motor I am aware of the risk and have had a lot of fun with this build so far. But it would nice if the head would stay on.

Thanks for any input.

[theman53]

There is a code on the front of the block. Stamped by the #3 injector. Find it and it will tell you/us what block you have. Being that it is that old anything could happen but if it was stock bolts then it probably is 11mm.

If the block is cracked it is done. If the hg is blown it could be replaced, but the 11mm are very touchy. If you could get a 12mm block I would try to go that route.

The single oil return is a mechanical head, they made 12mm mech heads too.

[matt-stunt]

Thanks the code you described that's stamped on the block is: 521 478


Just in case it helps, the castings on the front of the head are:

068 103 373
52
WWO
H

[RabbitJockey]

which psi is safe is really subjective to what turbo you have.

what size is the big crank bolt in the center of all the pulleys?

17mm would mean almost 99% of the time that you have an 11mm engine

19mm is a 12mm engine

[RabbitJockey]

which psi is safe is really subjective to what turbo you have.

what size is the big crank bolt in the center of all the pulleys?

17mm would mean almost 99% of the time that you have an 11mm engine

19mm is a 12mm engine

also if it took an allen socket then it's 11mm

pull the head, and inspect the block for cracks

if everything looks good, i would recommend studs(use the kit for an 8v gasser) but do not do a hot retorque

even still you run the chance of the block cracking when you tighten the studs... so its risky, but if all goes well you will have only spent about 150 dollars to be back on the road, if the block cracks you need a new engine.

plus who knows, your head could be warped.

[matt-stunt]

which psi is safe is really subjective to what turbo you have.

what size is the big crank bolt in the center of all the pulleys?

17mm would mean almost 99% of the time that you have an 11mm engine

19mm is a 12mm engine

also if it took an allen socket then it's 11mm

pull the head, and inspect the block for cracks

if everything looks good, i would recommend studs(use the kit for an 8v gasser) but do not do a hot retorque

even still you run the chance of the block cracking when you tighten the studs... so its risky, but if all goes well you will have only spent about 150 dollars to be back on the road, if the block cracks you need a new engine.

plus who knows, your head could be warped.

Thanks for the input. after doing some more reading about how these 11mm blocks are prone to cracking I am starting to think my block is good and cracked. While torqueing last night I noted that the 4 bolts on the outside corners felt "soft". And I just read that those are the most common to cracking around the bolt hole. You cant trust everything you read online but that's a heck of a coincidence if not the case.

[CRSMP5]

simple test....

let get cold...

fill coolent

with cap off start it... it it blows like a gyser.. time to pull the head..

[R.O.R-2.0]

doubt the block is cracked..

my old 1.5D saw 40+psi quite a few times before the block exploded..

i imagine if anything, your head gasket let go..

[ORCoaster]

Could be it just needs another cleaning, some Hylomar and reset.  Let us know.  Was the block in spec when you put it back into service?

[matt-stunt]

Thanks again guys for the replies. Got to looking at everything this evening and found the connector that blew apart was extremely brittle. Completely rotted plastic to the point where you could crumble it with your fingers. I replaced it then noticed that my V belt was missing. This explains my excessive coolant temperature last night as well as the connector blowing out. I'll have to get a belt tomorrow to see how my re-torque worked for the head leaking. Like I said previously, I can live with a seeping head gasket for now. Just hoping its not blown too bad as I do not have time or room in the shop for this project at the moment.

 

Could be it just needs another cleaning, some Hylomar and reset.  Let us know.  Was the block in spec when you put it back into service?

I bought this as a complete motor and didn't take the head off, the "If it ain't broke don't fix it" attitude.

I'll be sure to update when I get the belt and run it to see how the head gasket is holding up after re-torqueing. Meanwhile, in somewhat of a panic this afternoon I was searching and found an 84 1.6D long block available locally for $250. 170,000 miles. Bottom line this thing needs a head gasket when I get time. My thinking is if I'm doing a HG it'd be silly not to stud it which still leaves me with an 11mm block. For the extra 250 why not dress a 12mm block with my components with a fresh gasket and head studs. The big boost was a lot of fun and if I can do that reliably for reasonably cheap I think I should before putting any more time into this motor.

I know there are a lot of factors here but generally speaking what would be considered safe daily boost number through a studded 12mm engine?

Thanks again
-Matt

[vanbcguy]

I have run 20+ PSI for a looooong time without issues. K24 and a 2.5" exhaust on my side - keeping EGTs and exhaust manifold pressure in check is more important than the actual boost going in to the engine.

[RabbitJockey]

yes, make sure your egts are safe and that all your injectors are in good working order and you should be ok at nearly any boost level.  i think a very safe level tho with that turbo would be in the 15-20psi range, i wouldn't be shy about running 20psi either.

[matt-stunt]

Awesome. 20-25 was a lot of fun in that thing, like I said I did it only a couple times to see what it would do. Your suggestions are indeed regarding a 12mm engine with ARP studs correct? Sorry there is so much information and misinformation out there it's difficult to find specifics for my situation.

Regarding exhaust manifold pressure I'm sure it's pretty high when I open the veins (open being pointed toward the wheel / the more boost setting / lever on exhaust housing toward the ground). Someone correct me please if I'm explaining it backwards. I guess that's just something that comes with running a VNT15. My only option for correcting this would be a different charger.

My EGT has stayed rather low throughout my trials. Hasn't seen over 850 and that was running it pretty much flat out from a dead stop and my fuel screw is nearly maxxed. I'm sure it will get hotter when trying to pull hills and such but I'm very comfortable with the EGT situation. I do have a little bit on my side to keep things cool though. 2.5" exhaust from the turbo back, extra oil cooler, intercooler mounted on top sticking through the hood catching plenty of cold Pennsylvania November air, and a modified gasser intake manifold. So I think it's doing very well on the intake side. But the most important part between the head and the exhaust wheel is likely a different situation.  

Thanks again for the input. Really having fun with this project.

[RustyCaddy]

The part number on the head looks a little off...for a stock 1.6l block with 11mm head bolts it will mostly have a letter, usually a "B" or sometimes a "F" after the 373.  But there is some inconsistency to the letter coding.

There are some 373 heads without a letter trailing on 1.6 motors that have had the oil return boss built up on the outer lip to match the boss on the blocks oil return but they will still have the smaller inner diameter to the oil return (about the size of a nickel instead of the proper quarter size for the 1.6 head).  If there is a ledge showing on top of the block between the oil returns the head is built for a 1.5 l motor and that is a point of leakage.

If the block has a 16 cast into the the back side (not a 1.6) but a 1.5 liter head you are possibly running at a 25+ compression ratio before adding boost.  i had a 1.5 liter head on a 1.6 liter block for about 30000 miles and it ran good (it started really easy) but the pistons showed signs of melting below the pre-cup...the injectors (rebuilds from a local Bosch shop with France nozzles) might not have been dealing with the higher compression very well.

[745 turbogreasel]

The first thing that crosses my mind or EGT not  reaching 900 is you have the probe downstream from the turbo?