Bad HG or a Cracked head??

[IronFreak]

I'm pretty green when it comes to BMW's but not to the mechanical world in general. I fell in love with the e30's and after searching for a long time in my area I found one that was rust free (next to impossible in Nebraska on a 20+ year old car.) its a 1988 325iS, I literally stole it for a $1000 bucks. A lot had already been done to it but the guy I bought it from was mechanically illiterate. He couldn't tell me what had been done the the motor maintenance wise so I drove it straight home and put it in the garage. I was aware of engine problems when I bought it, it has the "thick milky" looking crap in the coolant system. What I thought was interesting was when I emptied the oil last night was it was perfectly clean, not one sign of coolant of moisture in it.



I'm going to do a leak-down test tonight and pull the valve cover, from a few post I've read that it's common for this head to crack between the 4-5 cam bearing channels I believe. But what do I know, that is why I'm posting on here. shoot me some feed back guys.

Thanks,

[jlevie]

The first thing I'd do would be to chemically flush the cooling system. Then see if the coolant remains clean.

1) Get the front of the car 1-2' in the air on jack-stands.

2) Drain the coolant, remove the thermostat, and set the heater controls for
full hot. O-ring sealed thermostats require you to make up a temporary
gasket, which can be made out of pasteboard.

3) Add flush compound and fill with plain water. Then run the engine at normal
temperature as specified by the flush manufacturer (usually about 15
minutes at operating temperature). In cooler weather it may be necessary to
block off some of the air into the radiator to decrease the warmup time.

4) Allow the engine to cool until you can place your hand on the cylinder head
w/o discomfort. Drain the system and refill with plain water.

5) Run the engine for 10-15 minutes or until temp is close to normal.

6) Repeat (4) and (5) until the water drained from the system is clear and
free of debris.

7) Fill with coolant. It is best to dilute aiitfreeze with distilled water.
Tap water contains disolved oxygen and may contain minerals. Either of
which will reduce the lifetime of the coolant.

Notes:

You don't absolutely need to remove the thermostat, but doing so will allow
continuous flow through the radiator and will also make draining & filling
faster and easier.

Always allow the engine to cool to the point that you can hold your hand on
the cylinder head without discomfort. That will prevent scalds from hot
coolant and prevent thermally shocking the head when you dump the coolant.

Filling the system with hot water makes the process go faster and keeps from
having to run the engine a lot in a cold condition (rich mixture).

A rusty cooling system needs an oxalic acid flush. Kits for that (containing
oxalic acid and soda for neutralizing the acid) used to be available, but
arent now. 8oz of oxalic acid and 4ox of soda will treat a 1-1/2 to 2 gallon
cooling system. The procedure is like the above with an extra step 4 where the
soda is added before the series of fill/drains are done.

[IronFreak]

Thank you for the tip, I will definitely try this. I would like to note that they guy I bought it from couldn't tell me if the timing belt had been replaced, so that's why I put it in the garage. there is oil leaking, and before I cleaned the block it looked as if it was below the head on the block. I was leaning towards a bad head gasket as I've been told there are two oil jackets that run through the block and the gasket might blow out. but I also know that if the cam seal is bad it can leak there. I tried to look into the head through the oil fill to see if the rocker shaft plugs are visible, but I didn't see them, are those even on a b25 head? I was reading the pelicanpart tech articles on replacing stuff, but I got to be careful as they seem to use e36 models with DOHC setups a lot.

[jlevie]

If the rocker shaft plugs are missing oil would be pouring out of the head. There are four of those and they should be changed every time the valve cover gasket is changed. Which should be done on every valve adjustment (every 10k).

[IronFreak]

Good deal, see I'm not completely in the dark! So your thoughts on the oil location. The seem and the head and the block meet, it was below that on the block only. does that sound like a head gasket?




Are these the oil jackets in the block I've heard people refer too?

[SpecM]

yes, but they can leak oil externally yet not present any other issues with coolant or internal leakage

what I'm saying is that they can leak, and the head gasket be still not "blown"

[IronFreak]

Yeah thats what I figured. I have had a few guys look at the sludge in my coolant tank, they keep trying to tell me I have oil in there. I'm just not buying that yet, and its not denial hahaha. I've been around motors that have coolant in the oil, I know what that looks like. This is a lite chocolate brown sludge, its not milky or watery. I think the coolant system needs to be flushed. Even though there isn;t internal leakage the HG still will need to be replaced. I'm going to do the leak-down just to verify, but the car seemed to run really strong. it just doesn't seem to have the right symptoms of a blown HG.

[IronFreak]

also, operating temperature is very stable. Frankly that blew my mind knowing that crap was in it. I had to drive it about 30 miles back to my house and there was no fluctuation with the temp.

[IronFreak]

Well I did a little more work on the car last night. I was worried about a crack in the top of the head from all the stuff I have read so I went right away and pulled the valve cover.



No milky foamy stuff in here, just nice a clean, I also took a snap shot of the top of the head.



I looked and looked and couldn't visibly see a crack......which doesn't mean much but it offered some relief. I also took some pictures if the spark plugs, below are plugs 1-6 in order.













Based on how they look what can you tell me on how the cars running?

Also, when I referred to a milky foamy substance I was talking about this.....



.....and this........



That is whats in my coolant reservoir. My one friend said maybe the previous owner didn't know where to put the oil hahaha. I'm still heavily leaning towards a head gasket as I have leaking on the block but not the head. I put it back together, I'm going to flush the coolant system tonight so its clean when I put the motor together.

Toss in your thoughts guys, let me know what you think or if there is something else I can check. I'll try doing a comp. test tonight, my buddy has a tool but never brought it over yesterday.

[Mr. Tasty]

that is perplexing, oil in coolant, but no coolant in the oil. PO probably didn't know where to put the oil haha

[IronFreak]

Ever since my buddy said that I am starting to wonder. it seems to run really well. What do you think about the plugs, they look really white. When I had the valve cover off I looked into the backside of the timing chain cover, from what I could see it looked dry, so I'm thinking that the oil that's leaking on the block is from the HG and not the cam seal.

[jlevie]

that is perplexing, oil in coolant, but no coolant in the oil. PO probably didn't know where to put the oil haha

Well, it would not be the first time that someone added oil to a cooling system instead of the engine, or other similar mistakes.

Oil in the coolant, but no coolant in the oil from a leaking head gasket would only mean that the leak is between a oil supply passage and a coolant passage. In that case since oil pressure is higher than cooling system pressure the oil flows into the coolant, but not the other way. Coolant in the oil results from a leak between a coolant passage and an oil return passage.

[travish325]

Looks like its running lean btw. Change those nasty plugs

[IronFreak]

Well as long as I can make it home (blizzard is coming) and flush the coolant I'll start pulling the head. travish.....I promise to change the plugs haha, I cleaned them up and stuck them back in so I could cycle the system, but new Bosch plugs will be used after the work is done.

[jlevie]

Well as long as I can make it home (blizzard is coming) and flush the coolant I'll start pulling the head. travish.....I promise to change the plugs haha, I cleaned them up and stuck them back in so I could cycle the system, but new Bosch plugs will be used after the work is done.

NGK ZGR5A plugs are better than what Bosch has now for these engines.