Hot Rod Forum banner

Coolant in oil. Need help identifying cause.

3145 Views 84 Replies 14 Participants Last post by  eric32
This is sort of related to my other post regarding a cam swap. In the process of learning more about that process, it was discovered that the dumped oil contains a good amount of coolant. The results of the oil test can be found here. Suffice it to say, there is coolant in the oil. So I am now taking a detour on my way to a different cam as this issue will have to be addressed first.

I am looking for help identifying where the coolant may be seeping into the oil. I will do a pressure test tomorrow, but for now I have pulled the spark plugs out and stuck an endoscope into all the cylinders. The results are below. Note that the truck has not been driven or started in about 3 days prior to my doing this work.
Insect Arthropod Pest Bottle Liquid

Font Auto part Metal Fashion accessory Engineering

Liquid Bottle Automotive tire Glass bottle Insect

Here are some picture from the endoscope. All pistons look about the same - pretty carboned up. Some, however, have what appears to be moisture. Can you guy draw any conclusions?

Gadget Display device Electric blue Font Electronic device

Font Display device Gadget Gas Output device

Azure Human body Gadget Entertainment Tints and shades

Gadget Font Flat panel display Display device Technology

Gadget Television set Automotive lighting Display device Gas

Azure Blue Purple Gadget Automotive lighting
See less See more
1 - 12 of 85 Posts
Those bolt holes on the 2 ends of each head go through the head and into coolant. I'm not speaking about exactly what the material is, but obviously for whatever reason there is a leak that deposited the material. It's good form to use liquid teflon sealer on the (cleaned) threads of any bolt that goes into the coolant (usually just do all intake and head bolts with sealer so torque is even). Wire brush the bolt threads and chase the threads in the bolt hole (removes any old sealer as well as junk).
  • Like
Reactions: 1
Well, gentlemen, I don't see any evidence of a coolant leak here:

View attachment 628639 View attachment 628640

It seems I am stuck on the horns of a dilemma. Pull the heads or not. My gut is telling me that pulling the heads WILL NOT reveal anything obvious. It's likely going to be a bunch of work for very little result. I will probably just end up changing the head gaskets and hope for the best. I do think that if there was an actual head gasket rupture, the pressure test would have revealed it.

There is something else I noticed though. Based on this doc, the head bolts have to be torqued to 70 ft/lb. I tested a few bolts in the middle of both heads and they were not even close to 70 fb/lb. I'm really tempted to just retorque the head bolts, add some K-Seal to the coolant and cross my fingers. Well, and, obviously swap the cam, cuz that's why I'm digging in there in the first place. What do yall think?
Pressure test may or may not show anything at all with a head gasket - you are giving the pressure test way more creedence than it deserves. It's impossible for you to simulate a running engine. Nix on any kind of sealer in the coolant. You shouldn't re-torque heads at this point.

Replace the head gaskets (use composition type head gaskets that do not require re-torquing), clean head bolt hole and head bolt threads, and look for cracks especially on cylinder #5. Check head surface straightness. Go back together with liquid teflon sealer as advised by others.

I'm curious. are the bottom of the bolt holes under the end intake bolts open to cooling passages, or are they just plugged up with gunk? See if you can stick a small screwdriver through the bottom of the bolt hole. Does any one know if these are blind holes on Dart Iron Eagles? If so, where did the gunk along the intake bolts come from.

Maybe you found out why the vehicle was sold? Maybe they already tried the pour sealer in the coolant? Stranger things have happened.
See less See more
Now the question becomes are you going to do a complete teardown and cleanup of the metal particles that have been circulating in your engine. Sorry.

Considering what these vehicles are worth, you might consider having a machine shop go through the short block and put the rest together yourself.
I will consider it. Sucks that a turnaround time for a good machine shop is going to be like 2 months. And I hate waiting. I hate waiting more than I hate doing things over.
Definitely looks like you found out why the vehicle was sold. My 2001 Blazer was something like that. Absolute creampuff - so much so that I was blinded to major engine problems. I ended up putting a Goodwrench crate engine in it so I could drive it in the snow that year instead of work on it. That was 70K miles ago.

At least it is Winter now and not Summer driving time!

The problem is that the microscopic metal particles go everywhere and will cause wear to happen much faster if they are not removed completely. We are not just talking about the lifter faces. We are talking about in the oil pasages, down the valve guides, in the rod/main/cam bearings, on the piston walls, oil pump gears, between the rings, etc. So maybe you get 20K miles instead of 100K miles (just as an example, not as fact). If the engine is otherwise fresh it seems a shame to not do it right before wear sets in.

This is in contrast to another thread I am involved in where just a cam is being done after multiple cam lobe failures. In that case we are just trying to get an old worn-out 305 running again. He has been warned a long time ago. I hope he remembers the warning and doesn't expect a long engine life. If he can get past the cam break in, he should be OK for some time until the metal particles have taken their toll on the rest of the engine. Yours would be the same.

If you have a place to work on it, and are willing to buy an engine stand and good torque wrench and anything else that you need - there is no reason why you can't disassemble and assemble short block yourself if that is interesting to you. Still need machine shop for washing block, polishing crank, and measuring things - but it would be a lot shorter wait I expect. If you find that the block needs major work for any reason, you might consider going to a late block that has factory roller cam provisions. Or you might just punt right away and stab a crate engine in - recouping part of the cost by selling your old engine. Or you could buy a short block kit. Lots of ways to go.
See less See more
Well, in Scottsdale where I live, 'tis the season for driving. Summer is when park your classic cars and wait till October.
Crate engine is the fastest way!
You read my mind. I was just browsing them. What do you think of this one?
Looks like a pretty nice little 355. I can't speak for Blueprint quality, but they make a lot of engines! This one has roller cam and 4-bolt mains - so good deal there. A little on the racy side at 390 hp but if you want some camshaft lope.... It would do you nicely with a good dual plane intake and a 750 CFM carb. But if it was me, for a truck I would be looking for a 383. So much more torque down low to get that heavy beast going after the stop light.
  • Like
Reactions: 3
A 390 hp 383 would run circles around a 390 hp 355, and be a lot more streetable in the process because max torque would be higher and occur at a lower RPM. Question is if he wants to pony up the difference in price.
390 horsepower is a measure of work accomplished. The result would be the same assuming the gearing of each engine was favorable to where that power appears on the RPM curve.

For sake of discussion, why don't we assume no gear ratio change and that engine will definitely not be operating at maximum horsepower at that stoplight?
  • Like
Reactions: 1
I'm not really looking for a lot of power. I want this truck to be a daily cruiser. If it makes 250 hp, I'm good. I want a reliable engine and if crate is the route I gotta go, so be it.
Then I am hearing the 383 is not worth the extra cost to you. I would snap up that 355 crate you spec'd before it is gone (last one at Summit). The price seems pretty good. Seems Blueprint is obsoleting them and changing to a version that uses their new block.
Quick questions. Head bolts. Watched a few videos on how to put them back on. Obviously they need some thread sealer as they go into the coolant jacket, but the videos all talk about having a thread locker on the bolts. So is it one or the other? Or is it one the same? I was going to put this on the threads and nothing else:
That's the stuff you want on clean dry threads. It is a PTFE sealer, not a thread locker.
1 - 12 of 85 Posts